Prepare the dough by making a well in the flour, and adding the salt, egg, and ¼ cup water in the centre. Using your fingers, work the ingredients together until dough is formed. If needed, add more water a spoonful at a time. Knead the dough on a lightly floured surface until smooth and elastic. Gather into a ball, place in a bowl, cover, and let rest for an hour.

Prepare the filling by mixing together in a bowl the grated onion, meat, parsley, salt, and pepper to taste. Set aside.

In a small bowl combine the yogurt and garlic, with salt to taste, if desired. Let sit at room temperature until ready to use.

Divide the dough into 2 balls. Roll out one ball of dough at a time on a lightly floured surface until very thin (about 1/16 inch). The secret of good dough is to roll it in different directions, not just in one direction. Cut strips 1 inch wide, then cut into 1-inch squares. Place about a ½ teaspoon of filling in the center of each square. Bring the four corners together over the filling and pinch to seal. Continue making manti until all the dough and filling are used. Place the manti on a lightly floured surface to lightly coat them.

Bring a large pot of salted water to a boil and in half the manti. As soon as they are cooked they will rise to the surface. Remove them from the pot with a slotted spoon and place in a serving bowl or individual bowls with a tiny bit of the cooking liquid. Cover to keep warm while cooking the remaining manti.

Pour most of the yogurt sauce over the manti saving the rest to pass in a serving dish. Quickly heat the butter in a small skillet and when the butter is sizzling hot, quickly add the pepper, mixing well. Remove from the heat and drizzle over the yogurt sauce. Sprinkle with sumac if desired. Serve manti at once with yogurt sauce. Manti can be frozen.