In a large mixing bowl, combine the flour and salt.
Gradually add the water and vegetable oil (or melted butter), mixing until a dough forms. If the dough is too dry, add a little more water, a tablespoon at a time.
Knead the dough on a lightly floured surface for about 5-7 minutes, or until it is smooth and elastic.
Cover the dough with a damp cloth and let it rest for at least 30 minutes.
In a bowl, combine the ground lamb or beef, finely chopped onion, chopped parsley or cilantro, ground cumin, ground coriander, salt, and black pepper.
Mix well to combine all the ingredients thoroughly.
Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Divide the dough into small portions and roll each portion into a thin circle on a lightly floured surface, about 4-5 inches (10-12 cm) in diameter.
Place a spoonful of the filling in the center of each dough circle.
Fold the dough over the filling to form a triangle or a square, pressing the edges to seal tightly. You can also shape them into half-moons if desired.
Place the filled somsa on the prepared baking sheet.
Brush the tops with the beaten egg to give them a nice golden color when baked.
Sprinkle with sesame seeds if desired.
Bake the somsa in the preheated oven for about 25-30 minutes, or until they are golden brown and cooked through.
Remove the somsa from the oven and let them cool slightly before serving.
Enjoy your meal!