In a bowl, combine the sliced lamb, cumin powder, minced garlic, grated ginger, salt, and pepper. Mix well and let it marinate for at least 30 minutes.

Heat the vegetable oil in a large pot or wok over medium heat. Add the marinated lamb to the pot and stir-fry until it's browned and cooked through. Remove the lamb from the pot and set it aside.

In the same pot, add the sliced onion and minced garlic. Sauté until they become fragrant and slightly caramelized.

Pour in the broth and soy sauce, and bring the mixture to a simmer. Let it cook for about 10 minutes to allow the flavors to meld together.

While the broth is simmering, cook the hand-pulled noodles in a separate pot according to the package instructions. Once cooked, drain and set aside.

Once the broth is ready, add the cooked lamb back into the pot. Stir to combine and let it simmer for another 5 minutes to heat the lamb through.

To serve, divide the cooked noodles into bowls and ladle the cumin lamb soup over the noodles. Garnish with fresh cilantro or green onions.