In a large bowl, combine the ground beef, cooked lentils, onion, egg, garlic, cumin ginger, chili powder, salt, and black pepper. Use your hands to mix it together until well combined. Form mixture into 20 meatballs (approximately 1 ½- to 2-tablespoons each) and place them on a plate.
Heat 1 tablespoon oil in a large skillet or saucepan over medium-high heat and swirl the pan around to distribute the oil. Add the meatballs to the pan and cook until browned on one side, 5-6 minutes.
While the meatballs are heating, in a bowl, combine the tomato sauce, coconut milk, ground cumin, ginger, chili powder, salt, and pepper.
Gently turn the meatballs over in the pan to brown the other side. Pour the sauce mixture over the meatballs.
Turn the heat to low or medium-low to hold a very low simmer. Cover the pan and let the meatballs and sauce cook for 15 minutes.
Remove the lid and thicken the sauce: In a small bowl, combine the 1 tablespoon cornstarch and 1 tablespoon of the liquid from the pan; stir together to make a thick slurry. Stir the slurry back into the sauce in the pan and allow it to return to a low simmer to thicken. Then, remove the pan from the heat and allow it to sit, it will thicken more as it cools slightly.
If desired, serve the saucy meatballs with Israeli couscous or rice. Garnish with fresh cilantro.
