SUMAC-SPICED LAMB PITAS

Name: Sumac-Spiced Lamb Pitas
Ingredients: 1/2 small white onion (roughly chopped); 1 small tomato (roughly chopped); 9 ounces ground lamb; 1 teaspoon sumac; 1/2 teaspoon baharat (Lebanese 7-spice); 1/2 teaspoon allspice; small handful parsley; pinch salt; 8 small pitas; 1/4 cup grated parmesan; za'atar (for sprinkling); feta cheese (for sprinkling)