Prep your red onions, sliced tomatoes, and fresh basil.
In a bowl, add tomatoes, onions and basil. Set aside.
In a new small bowl, whisk together olive oil, red wine vinegar, salt and pepper.
Pour oil mixture over tomatoes and mix well.
Let tomatoes and onions marinate for 20 minutes at room temperature.
If you choose to refrigerate, please note that olive oil is a fat and solidifies to an extent after long periods in colder temperatures. Make sure you bring salad to room temperature for 30 minutes and then stir to liquefy olive oil in salad prior to serving. This is with all olive oils.
See article for ingredient substitutions that you can add to this easy marinated tomato salad.
You can chop or slice red onions
I have also used 2 large tomatoes in place of 3 medium tomatoes