This recipe is from Xinjiang Province in the northwest corner of China. A land populated by the Uighur people who are Muslims of Turkic descent and carry with them culinary traditions rooted in ancient Middle Eastern techniques.
Beat the egg with the cornstarch in a large bowl. Toss in the lamb so that all the cubes are coated, and refrigerate for 1 hour.
Prepare a medium fire in a charcoal or gas grill and oil the grill grates. Dry-roast the cumin and coriander seeds in a skillet over medium heat just until you smell the spices aroma; be careful not to let them burn.
Then immediately remove the skillet from the heat and let cool. In a mortar and pestle or a coffee grinder, grind the seeds into a coarse powder.
Mix the powder with the salt and chili powder until well combined.
Thread 5 cubes of lamb onto each skewer and rub the spice mixture all over the meat. Brush the tops of the skewers with the oil.
Grill the skewers until they are crusty and brown on the outside and medium-rare on the inside. Serve the kebabs with a side of yogurt for dipping.