Add all of the ingredients to a medium-sized bowl except the lemon.
Squeeze the juice of ½ a lemon and pour it over everything in the bowl.
Stir.
If needed, squeeze the other half of the lemon and add to the bowl.
Taste for salt and pepper, and adjust as needed.
Garnish with sumac and serve or refrigerate for later.
For best results, let sit in refrigerator for a couple hours before serving.
