In a large mixing bowl, combine the flour and salt.
Add the egg and gradually add water, mixing until a soft dough forms.
Knead the dough for about 5-7 minutes until smooth and elastic. Cover with a damp cloth and let it rest for about 30 minutes.
In a bowl, combine the ground beef or lamb, finely chopped onion, ground cumin, black pepper, paprika, and salt. Mix well.
Divide the dough into two portions. On a floured surface, roll out one portion into a thin sheet (about 1/16 inch thick).
Cut the dough into small squares (about 1.5 inches in size).
Place a small amount (about 1/2 teaspoon) of the meat filling in the center of each dough square.
Fold the corners of the square towards the center, pinching them together to form a small bundle. Repeat with the remaining dough and filling.
Bring a large pot of salted water to a boil.
Gently drop the manti into the boiling water and cook for about 8-10 minutes, or until they float to the surface and are cooked through. Drain the manti.
In a small bowl, mix the plain yogurt with minced garlic and salt. Set aside.
In a small saucepan, melt the butter over low heat. Stir in the paprika and ground red pepper (if using), and heat for 1-2 minutes until fragrant.
Place the cooked manti on a serving plate.
Drizzle the yogurt sauce over the top, followed by the melted butter sauce.
Garnish with dried mint, fresh parsley, and a sprinkle of sumac (if using).
Enjoy your meal!