Bukharian Goshtgizhda (Savory Meat-Filled Pies)

Ingredients

• 1 ½ tablespoons active dry yeast (2 packets)
• 1 cup lukewarm water, divided
• 1 teaspoon sugar
• 1 ⅓ lb. all-purpose flour, sifted, plus more for work surface
• ½ cup olive oil, plus more for oiling
• 2 teaspoons salt
• 1 lb. onions (about 3 large), finely chopped
• 1 ⅓ lb. ground beef (mixed with 3 ounces of lamb fat - optional)*
• 1 teaspoon cumin seeds
• 1 egg, whisked