Halve the peppers, remove the seeds and grill with the cut surface facing down until the skin becomes blistered and black. Let cool, peel and cut into 2 cm pieces.
Cut tomatoes into 2 cm pieces. Mix the peppers and tomatoes.
To prepare the vinaigrette: stir together vinegar, pepper, sugar, garlic and olive oil.
Pour the vinaigrette over the salad and let it steep for 10 minutes so that the flavors can unfold.