Begin by slicing the red onion into thin rings and soak them in a bowl of ice water for 10 minutes.

Wash and dry the four ripe tomatoes, then cut them into thin wedges and place them in a large mixing bowl.

Take a small handful of basil leaves, roll them tightly, and slice them thinly to create a chiffonade.

Drain and pat dry the soaked onion rings, then add them to the tomatoes in the mixing bowl.

In a small bowl, whisk together the olive oil and red wine vinegar until well combined, then pour over the tomato-onion mixture.

Gently toss the salad, season with salt and pepper, garnish with basil, and let it sit for about 30 minutes before serving.