Place the lentils in a saucepan, cover with water, and bring to a boil. Reduce heat and simmer for about 20 minutes until tender but still holding their shape. Drain and let cool slightly.
Using a fork or potato masher, gently mash the cooked lentils, leaving some texture. Transfer to a large mixing bowl.
Add the ground meat, breadcrumbs, beaten egg, minced garlic, chopped parsley, cumin, and chopped onion to the lentils. Mix everything together with your hands until well combined; the mixture should be firm but pliable.
Shape the mixture into evenly sized balls, about the size of a golf ball, using your hands. Place them on a tray or plate.
Heat the olive oil in a frying pan over medium heat until shimmering. Carefully add the meatballs, making sure not to overcrowd the pan.
Fry the meatballs, turning occasionally, until they’re golden brown and cooked through—about 8-10 minutes. They should have a crispy exterior and a tender interior.
Remove the meatballs from the pan and drain on paper towels if needed. Serve hot with your favorite sauce or as part of a larger meal.
