Heat 1 tablespoon olive oil in a frying pan, then add in the sausage. Brown the sausage while breaking it into smaller pieces. Place the sausage to the side.

In the same pan, heat the second tablespoon of olive oil and add the celery, carrot, and onion. Cook, stirring often, until the onion is tender and translucent, approximately 5 minutes.

Add the ground cumin, crushed red pepper, and garlic to the vegetables. Continue to stir until the spices are well mixed in, approximately 1 minute.

Transfer the sausage and the vegetables into a stockpot, then add the chicken stock and lentils. Stir occasionally over medium heat until the soup reaches a near boil, then reduce the heat to low.

Simmer the soup, uncovered until the lentils are cooked and tender, approximately 35 to 45 minutes.

Season with salt and pepper to taste. Serve with crusty bread.