Cube lamb leg into 1/2” (1-cm) cubes (or just use ground lamb) and add it to a medium-sized bowl. Add the rest of the marinating ingredients. Mix well and allow to marinate at room temperature for about 15 minutes while preparing the other ingredients.

Add water to a large pot and bring to a boil. Cook the noodles according to instructions. Then transfer to a colander to drain. Run the noodles with cold tap water to stop cooking. Drain again and set aside.

Heat 1 tablespoon of oil in a large skillet over medium-high heat until hot. Add the lamb and spread out with minimal overlap. Cook, stirring occasionally, until the surface turns light brown but the meat is still slightly pink inside, about 2 minutes. Transfer the lamb to a plate and set aside. Save the oil in the skillet.

Pour in the remaining 1 tablespoon of oil. Add the onion. Stir and cook for 2 to 3 minutes, until the onion starts to soften.

Add the garlic and chili flakes. Stir and cook to release fragrance. Add the tomato. Stir and cook for 2 to 3 minutes, until the tomato starts to break down. Add the light soy sauce, tomato paste, cumin powder, sugar, and salt. Stir and cook to mix everything well, until the tomato has broken down and becomes saucy.

Add the pepper. Stir and cook until just softened but still crisp, 1 minute if using anaheim pepper, 2 to 3 minutes if using bell pepper.

Return the lamb back to the skillet and stir to mix well. Cook just long enough so the lamb is warmed through and not overcooked. If you’re using ground meat, you can cook it a bit longer to release more flavor and it won’t overcook.

To serve the noodles, fluff the noodles again and transfer to each serving plate. Add the noodle sauce. Stir to mix well and enjoy while hot!