5 from 1 votes

Tomato Onion Salad

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This balsamic vinegar marinated tomato onion salad is smothered in red onions and fresh herbs and makes a great choice for a tomato side dish platter.

Delicious sweet flavors paired with the pop of red onion make this colorful, easy side dish recipe a winner for lunch or for a party. Plus, I love that prep for this non-traditional salad only takes 15 minutes.

marinated salad recipe with red onoins.

Sliced tomatoes make great salads

Quick dishes are not always synonymous with great dishes. But sliced tomato and onion salad with balsamic is one of the quickest preps ever.

And while we do recommend letting tomatoes officially marinate in a garlic and vinegar mixture, the truth is that you still get quite a bit of full-figure flavor even if you don’t want to marinate.

tomatoes on the vine.

Salad Ingredients

  • large fresh tomatoes: A serrated-edged knife works excellent for thinly slicing larger tomatoes.
  • red onion
  • balsamic vinegar (or use red wine vinegar)
  • juice of half a lemon
  • Herbs and Seasonings: chopped fresh basil, fresh parsley, kosher salt, fresh ground black pepper, and minced garlic.

How to make Marinated Tomato and Onion Salad

  1. Slice ripe tomatoes about 1/4″ thick and place them on a serving platter or in a shallow dish. Set aside.
  2. Mix red onion, garlic, vinegar, lemon juice, basil, and parsley, and drizzle on top of the tomatoes.
  3. Cover and refrigerate tomato slices, marinating for at least 2 hours, flipping tomatoes halfway through marinating. Serve with salt and pepper.
sliced tomato salad with red onions.

Few tips to make the best of this recipe

  • Type of tomatoes – We love using vine-ripened tomatoes or large beefsteak-slicing tomatoes for the best presentation. There are a variety of tomato salad recipes that include cherry tomatoes or grape tomatoes, and those work best when you are using mozzarella balls. 
  • Fresh herbs only! There is nothing worse than dried herbs layering beautiful fresh fruits and veggies. It just doesn’t work for a beautiful look or flavor profile.
  • Always use fresh basil leaves and fresh parsley for salads. And not just this salad, but all salads.
  • This is a great recipe going into tomato season if you have a lot of tomatoes to use up.
  • Try feta cheese or goat cheese over the top.
tomatoes on a spatula.

How long will marinated tomatoes last in the fridge?

Tomatoes begin getting soft and leaking out all that juice once cut, so we recommend making and eating it within a day. However, property sealed in an airtight container, sliced tomatoes can last approximately 2-3 days and be served as a pairing with burgers, chicken or left as a meal on its own. 

tomato side dish recipe.
  • When it comes to summer salads, there really are a ton of choices. I personally enjoy a Caesar salad if I am at a restaurant, but when making at home, prefer more unique choices like pea salad or carrot salad. Or, if you want to stick with tomatoes, here are some of my favorite ways to use up the rest of those slices below.
5 from 1 votes

Tomato Onion Salad

Prep Time 10 minutes
Sliced Beefsteak Tomatoes marinated in red onions, fresh basil and Balsamic vinegar, easy tomato side dish with stunning color and huge bold flavors.


  • 4 large tomatoes on the vine
  • ½ cup red onion diced
  • 1 tbsp. minced garlic
  • 2 tbsp. balsamic vinegar (or use red wine vinegar) 
  • juice of half a lemon
  • 1 tbsp. chopped fresh basil
  • 1 tbsp. chopped fresh parsley
  • salt and pepper


  • Slice tomatoes about 1/4" thick and place onto a serving platter or in a shallow pan. Set aside.
  • Mix together diced red onion, minced garlic, Balsamic vinegar, lemon juice, fresh basil and fresh parsley and drizzle on top of sliced tomatoes.
  • Cover and refrigerate, marinating for at least 2 hours, flipping tomatoes halfway through marinating.
  • Serve with a sprinkle of salt and freshly ground black pepper. Delish!


  • We love using vine-ripened tomatoes or large beefsteak slicing tomatoes for the best presentation. 
  • Try sprinkling some feta cheese or goat cheese on top before serving.


Serving: 3slices | Calories: 24kcal | Carbohydrates: 5g | Protein: 1g | Fat: 0.2g | Saturated Fat: 0.03g | Polyunsaturated Fat: 0.1g | Monounsaturated Fat: 0.03g | Sodium: 6mg | Potassium: 205mg | Fiber: 1g | Sugar: 3g | Vitamin A: 607IU | Vitamin C: 11mg | Calcium: 11mg | Iron: 0.3mg

Nutritional Disclaimer: The nutritional data provided here is auto-calculated and intended for your convenience only. As it’s generated via automation, its accuracy may be compromised. For precise nutritional insight, please compute the values utilizing the actual ingredients in your recipe through your chosen nutrition calculator or application.

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5 from 1 votes

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