Wash the bulgur wheat, drain any excess water, and set aside for 15–20 minutes to soften.
Heat olive oil in a pan. Add the diced onions and sauté until soft and golden. Add the ground beef, seven spice, salt, and black pepper. Cook until the meat is fully cooked. Add butter or beef tallow if using, then set aside to cool.
Add the flour, salt, black pepper, cumin, seven spice, and dried mint to the softened bulgur. Gradually add water while kneading until a soft, workable dough forms.
Take a small piece of dough, roll it into a ball, and make an opening in the centre. Add some of the cooled filling, then carefully close and shape into an oval or ball. Repeat until all the dough and filling are used.
Shape any leftover dough into small balls without filling.
In a large pot, whisk together the yogurt, water, egg, salt, and cornstarch (if using) until smooth.
Place over medium heat and continuously stir in one direction until the yogurt comes to a gentle boil and starts bubbling.
Gently add the stuffed kibbeh and dough balls. Cook over medium heat for approximately 10 minutes, or until fully cooked.
Remove from heat, sprinkle dried mint over the top, and serve warm. Enjoy!