This height-of-summer salad is so simple, be sure that every single ingredient is the best, including the red wine vinegar. You can prepare this up to one day in advance and the flavors keep getting better. Serve it alongside any grilled meal from burgers to fish. Even onion skeptics will be surprised how sweet it is.
Combine the onion, tomato and cucumber in a large salad bowl. Toss well with the salt and then add the vinegar to coat completely. Add the olive oil and pepper and stir well. Taste for seasoning, adding additional salt and vinegar for a vibrant and full-flavored salad.
Chill in the refrigerator for at least 1 hour before serving for the best flavors and to serve cold.