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A fresh, tangy tomato onion salad made with juicy tomatoes and thinly sliced red onions. Tossed in a bold olive oil and vinegar dressing, it’s the easiest side you’ll make all summer.
about this RECIPE tomato onion salad
This tomato onion salad is a simple yet flavor-packed side dish that’s ideal for summer. Juicy tomatoes and crisp red onions are tossed in a tangy vinaigrette, making it a natural partner for grilled meats, fish, sandwiches, or even enjoyed straight from the bowl. It’s light and bright, but the taste still packs serious flavor thanks to the sharp onion, sweet tomatoes, and herby vinaigrette.
The longer it sits, the better it gets. A quick rest in the fridge transforms it from “good” to “can’t-stop-eating-this.” You’ll want to make it ahead of time so it’s ready to go when dinner hits the table.
It’s naturally gluten-free, vegetarian, and a breeze to customize. You can toss in herbs, cheese, or spice it up depending on your vibe.
Why You’ll Love This Recipe
This salad is one that is simple, but really elevates any spread you might have going on. Here’s some of the reasons why I love it so much:
- Fresh summer flavor in every bite. Juicy tomatoes, crisp onions, and a tangy vinaigrette come together in a salad that’s as refreshing as it is simple.
- Perfect for make-ahead. This salad gets even better after chilling, making it an ideal side for picnics, barbecues, and weeknight dinners.
- Naturally gluten-free and vegetarian. Light, customizable, and packed with bold flavor.
- 5-minute prep, no cooking required. Because summer salads should be stress-free.
ingredients
extra virgin olive oil. Adds rich, smooth body to the dressing and helps carry the flavor throughout the salad. It clings to every tomato and onion slice.
white wine vinegar. Crisp and tangy, this vinegar gives the salad its signature bite. It balances the sweetness of the tomatoes and adds that zippy, refreshing finish.
salt. Not just for seasoning! The salt pulls out the juices from the tomatoes, creating naturally flavorful juices that meld with the dressing as the salad chills.
granulated sugar. Totally optional, but a pinch can really balance out the acidity of the tomatoes in the salad.
red pepper flakes (optional). A little sprinkle gives the salad a soft heat.
chopped fresh basil. Brings a burst of fresh flavor that ties the whole salad in the dressing. Stir it into the dressing or sprinkle it on just before serving.
red onion. Sliced super thin, so it adds crunch without taking over. Soaking it in ice water can take down the sharpness if you prefer.
tomatoes. The heart of the salad! Opt for ripe, juicy tomatoes. Chop them chunky for texture and maximum flavor release.
tools to make this tomato onion salad
A big mixing bowl is key for tossing everything together and letting those juices do their thing. You’ll also want a small bowl to whisk up your dressing. It comes together fast, so just grab what’s handy.
A sharp knife and sturdy cutting board make quick work of the tomatoes and onions. If slicing onions thinly feels intimidating, a mandoline is fantastic for precision.
here’s how to make this tomato onion salad
Whisk
Add extra virgin olive oil, vinegar, salt, sugar (if using), red pepper flakes (if using), and basil in a small bowl. Whisk until well-combined. Make sure that the dressing is emulsified to coat the salad evenly.
Mix
Combine onion slices and chopped tomatoes in a large bowl. Pour the dressing over the top, then toss to coat.
Chill
For the best flavor, let the salad rest in the refrigerator for at least 4 hours before serving to allow the flavors to intensify.
Serve
Serve with a drizzle of freshly chopped basil and freshly cracked black pepper.
💬 behind the recipe
This tomato onion salad is one of my go-to summer sides. It was inspired by the fresh tomato salads I had the first time I went to Greece. The simple ingredients always stole the show. I wanted a version that felt classic yet versatile, made for pairing with smoky grilled meats or spooning over crusty bread.
The magic here is in the balance: fresh tomatoes, sharp onion, and a zippy vinaigrette that soaks into every bite.
It’s also endlessly adaptable. Whether you add fresh mozzarella for a caprese-style twist, toss in extra herbs from your garden, or keep it clean and simple, this recipe lets summer produce shine.
Tips for Success
- Use the freshest tomatoes for the best flavor in your tomato and onion salad. Farmers market picks are ideal.
- Slice onions thinly; soaking in ice water can mellow sharpness if desired.
- Let the salad rest in the refrigerator for at least 4 hours to allow the flavors of the salad, including onion and tomato, to meld fully.
- Add a pinch of sugar to balance acidity if the tomatoes are tart.
- Fresh basil added before serving brightens this salad beautifully.
- Don’t skip the resting time! The longer it chills, the more flavorful it gets.
variations
Switch out the white wine vinegar for red wine vinegar or balsamic if you’re going for a sweeter twist on this tomato onion salad. Both bring a deeper, slightly richer tang that plays well with the tomatoes.
Add in fresh mozzarella, crumbled feta, or goat cheese to bulk things up a bit. Either one brings a creamier, salty element that turns this into more of a meal than a side.
For even more Mediterranean flair, toss in a handful of olives or extra herbs like parsley, mint, or oregano. They bring out that bright, briny edge that makes the whole dish pop.
Want a milder bite? Swap the red onion for thinly sliced shallots. They’re softer in flavor but still bring that signature crunch. And if you like heat, go bold with a pinch of red pepper flakes or a few fresh chilies.
More salad recipes to try: cucumber tomato salad I mango chicken salad I southwest chicken salad I burrata caprese salad
faqs
What are the best tomatoes to use?
Ripe, in-season tomatoes like heirloom, Roma, or cherry tomatoes are best for this recipe. Farmers market tomatoes offer unbeatable flavor and juiciness.
How do I mellow the onion flavor?
If red onions are too strong, soak the slices in ice water for 10–15 minutes before adding them to the salad. It softens the bite without losing the crunch. Or you can use sweet onions such as Vidalia.
Can I use dried herbs instead of fresh herbs?
Fresh basil really makes the flavor pop, but if you’re out, use a small pinch of dried basil. Just go easy, as dried herbs are more concentrated.
can I make this salad ahead?
Yes! It’s actually better to let it rest in the fridge for at least a few hours before serving so the flavors can meld.
Need some more salad inspiration? Check out my salad recipes page!
what to serve with this tomato onion salad
This salad shines next to anything hot off the grill. Serve it alongside bangin’ grilled shrimp for a light dinner, or pile it on a salmon sandwich for a fresh lunch upgrade.
It’s also dreamy with baked lemon garlic salmon, juicy grilled full chicken, or smoky, tender smoked chicken.
how to store
Store: Keep any leftovers in an airtight container in the fridge for up to 3 days. This salad is best served fresh, but it still holds up well for meal prep.
Freeze: Avoid freezing as tomatoes lose their texture once thawed.
more of our favorite Mediterranean recipes
Pair this with an Italian charcuterie board for the ultimate appetizer spread, or add it alongside a summery bowl of corn and tomato risotto. It also makes a great fresh contrast to a creamy scoop of Greek hummus and warm pita bread.
seasonal tip
Summer is prime time for tomatoes – hit up your local farmers market for the juiciest, most flavorful picks. Look for tomatoes that feel heavy for their size and have a deep, sweet smell at the stem. If you’re shopping out of season, cherry tomatoes are your best bet for consistent flavor.
Finally, if you make this tomato onion salad recipe, please be sure to give this recipe a star recipe rating on the recipe card and/or leave a comment! I love to hear when you all make recipes, and I do take the time to respond to every single comment.
Feel free to drop questions below too, if you have them!
Oh and be sure to tag me on Instagram, Facebook, or Pinterest if you make the recipe! I love being able to see these recipes come to life in your homes – it’s my favorite thing to look through those photos. It really means the world to me!
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tomato onion salad
ingredients
- ½ cup extra virgin olive oil
- ⅓ cup white wine vinegar
- ½ tsp salt
- Pinch of granulated sugar optional to balance flavors
- Pinch of red pepper flakes optional for added heat
- 2 Tbsp chopped fresh basil
- 1 red onion thinly sliced
- 4 tomatoes chopped
- Freshly chopped basil for garnish
- Freshly cracked black pepper to taste
instructions
- Add extra virgin olive oil, vinegar, salt, sugar (if using), red pepper flakes (if using), and basil in a small bowl. Whisk until well-combined.
- Combine onion slices and chopped tomatoes in a large bowl. Pour the dressing over the top, then toss to coat.
- Let rest in the refrigerator for at least 4 hours before serving to allow the flavors to intensify.
- Serve with a sprinkle of freshly chopped basil and freshly cracked black pepper.
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about meghan
Meghan Yager is the recipe developer, food photographer, and creative force behind Cake ‘n Knife, where everyday moments are celebrated with bold, flavor-forward recipes. From cozy cocktails to bold appetizers and indulgent desserts, her approachable style brings people together around food worth sharing. Meghan’s work has been featured by Good Housekeeping, Oprah Daily, Today, Woman’s Day, and The Huffington Post. She lives in Denver, where she brings big flavor and a little sass to every bite.
