Tomato and Onion Salad

4.60 from 10 votes
20 minutes
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This easy Tomato and Onion Salad is the tomato salad to make this summer and every summer.  Fresh tomatoes take center stage with a supporting cast of a delicious light vinaigrette, thinly sliced red onion, capers for a salty, briny kick and lots of fresh basil!

Tomato Onion Salad on white oval platter.

Why This Recipe is a Keeper!

Tomato lovers like me wait all year to pick the first summer tomato because there’s nothing quite like one that’s homegrown.

Because the season is so limited, you don’t want to hide their amazing flavor. This Tomato and Onion Salad is a simple yet delicious way to enjoy summer tomatoes’ bright, juicy taste.

A light vinaigrette, salty capers and fresh basil pair perfectly with the natural sweetness of tomatoes. Together, these ingredients create a harmonious balance of flavors that elevate the taste of the fresh tomatoes, making each bite a burst of summery goodness!

This tomato and onion salad recipe:

  • Is super easy!
  • Showcases the freshness of summer tomatoes rather than disguise them.
  • Is the perfect side dish for all your other summer fare like grilled meats, poultry, fish, seafood and vegetables.

Let’s make it!

Tomato Onion Salad on white platter with serving fork.

How to Make a Tomato Onion Salad:

Recipe Ingredients:

Here’s everything you’ll need to make this tomato and onion salad recipe, along with how to prep the ingredients. See the recipe card below for the exact quantities.

Ingredients for Tomato Onion Salad in glass bowls.

Ingredient Notes and Substitutions:

  • Tomatoes: The most important ingredient! Use fresh summer tomatoes from your backyard, the farmers’ market or a friend’s bounty! Any tomato will work, such as Beefsteak, Romas or even cherry and grape.
  • Red Onion: I love onions, but if you don’t, go easy or dice the onion and sprinkle them over the top.
  • Red Wine Vinegar: Red wine vinegar is fermented red wine. Bacteria and oxygen are introduced to red wine to transform it into acetic acid, which gives vinegar its distinctive tangy flavor. After fermentation, the vinegar is diluted to achieve approximately 5% acidity. Pompeiian is a reliable brand.
  • Dijon Mustard: I’ve tried numerous brands of Dijon mustard, and you can’t go wrong with Grey Poupon which is widely available in every supermarket. Grey Poupon originated in Dijon, France in the 1800’s. Although Kraft Heinz now owns it, it has authentic roots. Maille is also good, but it’s pricey.
  • Capers: Capers are green, unripened flower buds of the caper bush. They’re available near the pickled products section.
  • Sugar: Just a pinch is needed! It helps to bring out the natural sweetness of the tomatoes.
  • Fresh Basil: A must!

Step-By-Step Instructions:

  • Gather and prep all the ingredients.
  • Whisk together olive oil, red wine vinegar, mustard, garlic, sugar, salt and black pepper to taste.
  • MAKE AHEAD: The vinaigrette can be made up to three days ahead, but wait until you’re almost ready to serve the salad to slice the tomatoes and onions and tear the basil.
Vinaigrette in glass bowl.
  • Place tomatoes on a serving platter.
Sliced tomatoes on white oval platter.
  • Top with red onion and capers.
  • Drizzle dressing over tomatoes.
  • Garnish with torn basil and whole basil leaves. Serve immediately.
Tomato Onion Salad with vinaigrette drizzled over it garnished with fresh basil leaves.
  • Enjoy! You’ve got the best Tomato and Onion Salad to pair with anything!  An easy vinaigrette, pure and simple sliced tomatoes, red onions, capers, and fresh basil for pure summer enjoyment!
Tomato Onion Salad on white oval platter.

Chef Tips and Tricks:

  • Always store tomatoes at room temperature. The cold refrigerator air steals the flavor and makes the tomatoes mealy.
  • When making a vinaigrette, all the ingredients–especially the oil–should be at room temperature because cold ingredients make it difficult to create an emulsion. Let the vinaigrette stand at room temperature for the flavors to meld while making the rest of your salad.
  • Use a serrated or razor-sharp knife to slice tomatoes. This enables you to slice through the skin without crushing the flesh.
Tomato Onion Salad on white oval platter with serving fork.

Frequently Asked Questions:

What are the best tomatoes for a salad?

Almost any tomato will work in this salad, although I don’t recommend green tomatoes. Beefsteak tomatoes hold their shape, plum are less watery, and cherry and grape tomatoes just need a quick halving.

Can I make this Tomato and Onion Salad ahead of time?

The vinaigrette can be made up to three days ahead of time but wait until you’re almost ready to serve the salad to slice the tomatoes and onions and tear the basil.

Tomato Onion Salad on white oval platter with serving fork.

Storage:

  • Store any leftover salad in the refrigerator. Let stand at room temperature for 30 minutes or so before enjoying the leftovers.

Serve with:

More great tomato salad recipes you’ll love!

Get all my side salad recipes at Side Salad Recipes – From A Chef’s Kitchen.

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Tomato Onion Salad on white oval platter.

Tomato and Onion Salad

4.60 from 10 votes

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By: Carol | From A Chef’s Kitchen
This easy Tomato and Onion Salad is the tomato salad to make this summer and every summer.  Fresh tomatoes take center stage with a supporting cast of a delicious light vinaigrette, thinly sliced red onion, capers for a salty, briny kick and lots of fresh basil!
Prep Time 20 minutes
Total Time 20 minutes
Course Side Dishes – Salads
Cuisine Italian
Servings 4
Calories 195 kcal

Ingredients
  

  • 1/3 cup extra-virgin olive oil
  • 2 tablespoons red wine vinegar
  • 2 teaspoons Dijon mustard
  • 2 cloves garlic - minced
  • 1/2 teaspoon sugar - or to taste
  • 1 teaspoon salt - or to taste
  • Freshly ground black pepper - to taste
  • 4-5 medium tomatoes - sliced
  • 1/2 medium red onion - thinly sliced
  • 2 tablespoons drained capers
  • 4 sprigs fresh basil - leaves only, torn with some left intact for garnish

Instructions
 

  • Whisk together olive oil, red wine vinegar, mustard, garlic, sugar, salt and black pepper to taste.
  • Place tomatoes on a serving platter.
  • Top with red onion and capers.
  • Drizzle dressing over tomatoes.
  • Garnish with torn basil and whole basil leaves. Serve immediately.

Notes

MAKE AHEAD:  The vinaigrette can be made up to three days ahead of time but wait until you’re almost ready to serve the salad to slice the tomatoes and onions and tear the basil.
When making a vinaigrette, all the ingredients–especially the oil–should be at room temperature because cold ingredients make it difficult to create an emulsion. Let the vinaigrette stand at room temperature for the flavors to meld while making the rest of your salad.

Nutrition

Serving: 1 | Calories: 195kcal | Carbohydrates: 7g | Protein: 2g | Fat: 18g | Saturated Fat: 3g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 13g | Sodium: 728mg | Potassium: 332mg | Fiber: 2g | Sugar: 4g | Vitamin A: 1138IU | Vitamin C: 19mg | Calcium: 26mg | Iron: 1mg

These are estimated values generated from a nutritional database using unbranded products. Please do your own research with the products you’re using if you have a serious health issue or are following a specific diet.

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4.60 from 10 votes (8 ratings without comment)

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Recipe Rating




6 Comments

  1. A perfect salad to make with our fresh-from-the-garden tomatoes and basil. Love the addition of the capers! Tasty!

    1. Thanks so very much, Margo! So glad you enjoyed! I love adding capers whenever possible; they sure add an extra pop of flavor. Thanks again!

  2. 5 stars
    The sunlight on those tomatoes is everything! Love the addition of the capers to this wonderful summer salad. Such a great back pocket recipe for when it’s too hot to cook!

  3. 5 stars
    Sliced tomatoes are on my table every night when they are in season. I love the idea of adding that dressing

    1. Thanks, Anne! During tomato season, I want to eat ALL the fresh tomatoes or as many as I can! The dressing is perfect with the tomatoes! Thanks again!