If fresh ripe tomatoes aren't available, you can substitute canned whole tomatoes. Use white wine vinegar or red wine vinegar in place of the sherry vinegar in a pinch.
1 cucumber, peeled, seeded, and chopped
1 large ripe tomato, chopped
1/2 cup jarred roasted red peppers, chopped
1 celery rib, chopped
1 garlic clove, minced
1 tablespoon extra-virgin olive oil
1/2 tablespoon sherry vinegar
1 teaspoon lemon juice
1/4 teaspoon salt
1/8 teaspoon pepper
1. Combine all ingredients in a medium bowl; cover mixture, and chill.