Prepare the tomatoes by selecting ripe heirloom or vine-ripened tomatoes. Rinse gently, slice into wedges or bite-sized pieces, and set aside in a bowl.

Chop the fresh basil by rinsing the leaves, drying with a towel, rolling them tightly, and slicing into thin ribbons. Add to the bowl with tomatoes.

Slice the red onion thinly, optionally soaking it in cold water for 10 minutes to reduce sharpness. Add to the tomato and basil mixture.

Drizzle olive oil over the tomato mixture, using about 2-3 tablespoons. Toss gently to coat.

Season with sea salt and black pepper, tossing again to ensure even distribution of flavors.

Add optional ingredients like feta or avocado. Mix gently without bruising the tomatoes.

Let the salad sit for 10-15 minutes at room temperature to enhance flavors before serving.

Transfer to a serving platter or individual bowls, garnishing with whole basil leaves if desired.