How to Make It
Make the dough: Combine warm water, sugar, and yeast in a small bowl. Let stand until foamy, about 10 minutes. Add 1/4 cup oil to yeast mixture, and stir to combine.
Stir together 3 1/4 cups flour and 2 1/2 teaspoons salt in a large bowl, and make a well in center of dry ingredients. Pour yeast mixture into well and gradually incorporate with a wooden spoon. When mixture becomes too stiff to stir and forms a shaggy dough, transfer to a lightly floured surface and begin kneading by hand, adding up to remaining 5 tablespoons flour, 1 tablespoon at a time, if dough is too sticky. Knead until dough is soft and elastic, about 10 minutes. Grease a large bowl with oil, and place dough in bowl, turning to coat. Cover with plastic wrap, and let rise in a warm place until doubled in size, about 1 hour.
Make the filling: Coarsely chop spinach. Place in a clean kitchen towel, and squeeze out excess liquid. Place spinach in a large bowl; break apart into small pieces. Add onion, lemon juice, 2 teaspoons salt, pepper, allspice, cinnamon, and sumac; stir well to combine.
Preheat oven to 400°F. Punch down dough, and divide into 24 (1-ounce) pieces. Roll each piece into a ball; cover and let stand 10 minutes.
Using a floured rolling pin, roll out each ball into a 4-inch circle on a lightly floured surface. Keep flipping dough and dusting beneath with flour so dough doesn’t stick.
Make the pies: Place about 1 1/2 tablespoons filling in center of each pastry round. Shape into traditional triangle shape by pinching edges together to create 3 corners then pinching edges between corners together to enclose filling. Place pies on 2 lightly oiled baking sheets. Brush pies generously with oil. Bake in preheated oven until golden brown, 18 to 20 minutes, rotating pans after 12 minutes.