There’s something undeniably refreshing about crisp cucumbers, juicy tomatoes, and sweet onions mingling together in a tangy marinade. I grew up watching this bowl of summer colors make its way to every family cookout and dinner table—it was a staple that brought cool, clean flavors to balance out all the grilled meats and heavier sides. Over time, I started playing with the recipe, making subtle tweaks until I landed on this vibrant, herb-speckled version that never lasts long in my fridge.

What I love most about this marinated mix is how the vegetables soak up all the tangy, garlicky, slightly spicy flavors overnight. It’s perfect for meal prep—an effortless way to add freshness and crunch to any meal. You can spoon it over grilled chicken, pile it on a sandwich, or enjoy it straight from the jar (yes, I’ve done that more than once). Whether you’re planning a picnic or just craving a light, healthy snack, this colorful jar of goodness is a go-to.

Why You’ll Love This Marinated Cucumbers, Onions, and Tomatoes

It’s packed with vibrant flavor. A simple marinade transforms basic veggies into something crave-worthy.
Ridiculously easy to make. Chop, mix, chill—done!
Healthy and guilt-free. Low in calories, high in crunch and hydration.
Versatile side dish. Pairs beautifully with proteins, BBQ, sandwiches, or wraps.
Make-ahead perfection. Tastes even better after a night in the fridge.

What Kind of Vinegar Works Best for Marinated Cucumbers, Onions, and Tomatoes?

When it comes to building flavor in this marinated veggie mix, vinegar plays the starring role. I prefer apple cider vinegar for its mellow tang and slight sweetness—it complements the tomatoes and onions beautifully. If you’re after a bolder kick, white vinegar does the job well with a sharper bite. For a more delicate taste and a little extra elegance, red wine vinegar is also a great option, especially if you’re serving this at a dinner party or alongside grilled seafood. Just steer clear of balsamic—it overpowers the fresh, clean flavors we’re going for here.

Options for Substitutions

This recipe is as flexible as it is flavorful. If you’re missing an ingredient or want to switch things up, here are some ideas:

Cucumbers: English or Persian cucumbers work best, but regular cucumbers (peeled if the skin’s thick) are just fine.
Tomatoes: Any cherry or grape tomatoes are perfect, but you can also dice up heirlooms or Roma tomatoes.
Onions: Red onions add a mild sweetness and color contrast, but white or sweet Vidalia onions work too.
Herbs: I usually use dried parsley and oregano, but feel free to add fresh dill, basil, or thyme if you have it.
Heat: Crushed red pepper adds a bit of kick—adjust it to your taste or skip it altogether.
Oil: Extra virgin olive oil is my go-to for richness, but any neutral oil like avocado or grapeseed works if needed.
Sugar substitute: Want it low-carb? Replace the sugar with a bit of honey or a sugar alternative like stevia or monk fruit.

Ingredients for Marinated Cucumbers, Onions, and Tomatoes

Every ingredient in this recipe plays a distinct role, coming together to create a dish that’s vibrant, crisp, and full of flavor. Here’s what you’ll need and why it matters:

Cucumbers – They bring the refreshing crunch. I like to keep the skins on for extra texture and color.
Cherry or Grape Tomatoes – These add sweetness and juicy bursts of flavor. Halved, they absorb the marinade beautifully.
Onion (Red or White) – Sharp and slightly sweet, onions give the salad its edge and aromatic bite.
Apple Cider Vinegar – This is the heart of the marinade, delivering tang and brightness to balance the sweetness of the tomatoes.
Olive Oil – A splash of good olive oil rounds out the acidity and gives the mixture a silky finish.
Dried Herbs (Parsley, Oregano) – These boost the savory profile and enhance the Mediterranean vibe.
Garlic – Minced or finely chopped, it adds depth and a little pungent zing to the mix.
Crushed Red Pepper Flakes – Just a pinch wakes everything up with a hint of heat.
Salt and Black Pepper – Essential for enhancing all the natural flavors.
Sugar (Optional) – A tiny bit helps mellow the vinegar and rounds out the marinade, especially if you’re using a more acidic vinegar.

Step 1: Slice the Veggies

Start by thinly slicing your cucumbers into even rounds—about ¼ inch thick works great. Next, halve your cherry or grape tomatoes so they can soak up more of the marinade. Then thinly slice your onion into slivers. If you’re using red onion and want to mellow the sharpness, you can soak the slices in cold water for 10 minutes and drain before using.

Step 2: Mix the Marinade

In a large bowl or a measuring cup with a spout, whisk together your apple cider vinegar, olive oil, minced garlic, dried herbs, crushed red pepper, salt, black pepper, and a pinch of sugar (if using). Stir well until everything is fully combined. You want the herbs and garlic to be evenly distributed for consistent flavor.

Step 3: Combine and Toss

Place your prepped cucumbers, tomatoes, and onions in a large bowl or jar. Pour the marinade over the vegetables and give everything a gentle but thorough toss. Make sure every piece is coated and submerged as much as possible in the liquid.

Step 4: Marinate and Chill

Cover the bowl with plastic wrap (or seal the jar) and refrigerate for at least 2–3 hours, though overnight is even better. The longer it sits, the more flavorful everything becomes. Give it a stir halfway through the marinating time to redistribute the flavors.

Step 5: Stir Before Serving

Right before serving, give the mixture a good stir to ensure all the marinade is well mixed. Taste and adjust seasoning if needed—maybe a pinch more salt or an extra splash of vinegar depending on your preference.

How Long to Marinate Marinated Cucumbers, Onions, and Tomatoes

While this dish doesn’t require any cooking, time is key for flavor. For the best results:

Minimum time: Let it marinate for at least 2–3 hours in the fridge. This gives the veggies time to absorb the tangy, herby flavors.
Ideal time: Let it sit overnight (8–12 hours) for maximum flavor infusion.
Maximum time: It holds up well for about 3–4 days, but by day 5 the cucumbers may lose their crunch.

So, if you’re prepping for a weekend BBQ or weekday lunches, you can easily make this a day ahead and it’ll only get better.

Tips for Perfect Marinated Cucumbers, Onions, and Tomatoes

Use firm, fresh veggies. Softer cucumbers or overripe tomatoes will break down too quickly in the marinade.
Slice evenly. Uniform slices help the vegetables marinate evenly.
Stir halfway through. If it’s sitting overnight, give the mix a toss after a few hours to redistribute the marinade.
Use a glass jar or bowl. Acidic ingredients like vinegar can react with metal, so avoid using metal containers.
Chill before serving. This dish is best served cold—it makes the crunch and zing pop even more.
Add fresh herbs before serving. If you love a burst of fresh flavor, toss in some chopped parsley or basil right before serving.
Taste before plating. Depending on the strength of your vinegar, you might want a touch more oil or sweetness to balance things out.

Watch Out for These Mistakes While Cooking

Even though this is a no-cook recipe, there are still a few pitfalls to avoid that can make the difference between a great marinated salad and a soggy one:

Using overly ripe tomatoes: Super soft tomatoes will fall apart in the marinade, turning mushy by the next day.
Skipping the chill time: The flavors need time to meld—don’t rush it. A quick 20-minute soak won’t deliver the same depth.
Not salting enough: A touch of salt brings out the natural sweetness of the veggies and balances the acidity. Taste and adjust!
Overcrowding the container: Make sure your vegetables have enough room to move around and absorb the marinade evenly.
Using metal containers: Always go for glass, ceramic, or food-safe plastic to avoid any off flavors from vinegar reactions.
Not stirring before serving: The good stuff tends to settle—make sure to toss it so every bite gets the full flavor.
Cutting veggies too thin: Thin slices get soggy fast. Keep your cuts around ¼ inch for the best texture.
Overloading with garlic or pepper flakes: These can intensify as they sit. It’s better to start mild and adjust later.

What to Serve With Marinated Cucumbers, Onions, and Tomatoes?

This fresh, tangy side can upgrade just about any meal. It’s endlessly versatile, and here are some great ways to enjoy it:

1. Grilled Chicken

The bright acidity cuts through smoky, savory grilled meats beautifully.

2. Burgers or Sandwiches

Use it as a topping or serve it alongside to add crunch and zest.

3. Fried or Grilled Fish

This dish brings a refreshing contrast to richer seafood flavors.

4. Quinoa or Couscous Bowls

Spoon it over warm grains for a quick lunch bowl packed with texture and flavor.

5. BBQ Ribs or Pulled Pork

It balances out heavier, saucy mains with something light and crisp.

6. Scrambled Eggs or Omelets

Yes, really! It makes a surprisingly good cold salad on the side of a warm breakfast.

7. Tacos or Wraps

Use it as a fresh veggie topping to add snap and a tangy bite.

8. Cheese and Charcuterie Boards

Pile it in a bowl next to meats and cheeses—it makes a delicious palate cleanser.

Storage Instructions

Marinated Cucumbers, Onions, and Tomatoes store exceptionally well, making them ideal for meal prep or make-ahead side dishes.

Refrigerator: Store the salad in an airtight container or glass jar in the fridge. It will stay fresh for up to 4 days. Just give it a stir each day to redistribute the marinade.
Best storage container: A wide-mouth mason jar or glass container with a lid works best to keep the veggies crisp and prevent any metallic interaction with the vinegar.
Freezing: Not recommended. The fresh vegetables will lose their texture and become watery after thawing.
Make-ahead tip: If prepping more than a day ahead, keep the marinade separate and mix it in a few hours before serving to preserve the cucumbers’ crunch.

Estimated Nutrition (Per 1-Cup Serving)

Keep in mind these are approximate values and can vary based on the exact ingredients and quantities used:

Calories: ~70 kcal
Total Fat: 4g (from olive oil)
Saturated Fat: 0.5g
Carbohydrates: 7g
Sugar: 4g (naturally from tomatoes + optional added sugar)
Fiber: 1.5g
Protein: 1g
Sodium: ~180mg (can vary based on added salt)
Cholesterol: 0mg

This makes it a low-calorie, low-carb, and refreshing side dish that’s also vegan and gluten-free—great for just about any eating style.

Frequently Asked Questions

What kind of cucumbers work best for this recipe?

I recommend English cucumbers or Persian cucumbers. They have thin skins, fewer seeds, and stay crisp longer in the marinade. If you’re using regular garden cucumbers, just peel them and remove large seeds for the best texture.

Can I make this recipe without oil?

Yes, you can skip the oil entirely if you’re going for an ultra-light version. Just note that the oil helps round out the acidity and carries the flavor. A small splash of water or vegetable broth can help dilute the vinegar if it feels too sharp without oil.

How long should I marinate the vegetables?

A minimum of 2–3 hours is great, but letting it sit overnight brings out the best flavor. It’s one of those dishes that gets better with time—up to about 4 days.

Can I use fresh herbs instead of dried?

Absolutely! Fresh parsley, basil, or dill can elevate the flavor and give it a garden-fresh feel. Add fresh herbs just before serving to keep their color and vibrance.

What if my tomatoes get too soft?

If your tomatoes are super ripe, they might break down in the marinade. To prevent that, add them just before serving, especially if you’re marinating the rest of the mix overnight.

Is this recipe suitable for a low-carb or keto diet?

Yes—just skip the sugar or use a keto-friendly sweetener like monk fruit, erythritol, or stevia. Everything else in the recipe is naturally low-carb.

Can I double the recipe?

Definitely! This recipe is easy to scale up. Just keep the veggie-to-marinade ratio roughly the same so all your ingredients get properly coated.

Can I use lemon juice instead of vinegar?

You can, though it will give a slightly different (and more citrusy) flavor profile. Vinegar is stronger and preserves the veggies better, but lemon juice works in a pinch for a fresh twist.

Conclusion

Marinated Cucumbers, Onions, and Tomatoes are the kind of dish that delivers maximum flavor with minimal effort. It’s light, bright, and the perfect way to add a refreshing, tangy crunch to just about any meal. Whether you’re prepping ahead for a busy week, planning a summer picnic, or just looking for something zippy to snack on, this recipe checks all the boxes: easy, healthy, flavorful, and satisfying.

It’s a staple in my fridge—and after one bite, I have a feeling it might become one in yours too.