
Mix the salad. In a large bowl, combine the bell peppers, tomatoes, scallions, dill, garlic, and olives. Sprinkle with the sumac and a large pinch of salt and pepper (about ½ teaspoon each).
Dress the salad. Add the lemon zest and juice along with the olive oil and give it a good toss. Taste and adjust the seasoning.
Rest and serve. If you have time, set aside for 20 minutes or so before serving to allow the flavors to meld.