In a large skillet or pot, add the oil and sauté the onion and garlic over low-medium heat for about 6-7 minutes.Add in the celery and sauté another few minutes. Stir in the spices and cook for another couple minutes on low.Now, rinse and drain the lentils and stir into skillet/pot. Add the broth and stir well. Increase heat and bring to a boil. Reduce heat to low, cover, a simmer until thick and lentils are cooked, about 45 minutes to an hour. Watch closely and stir frequently so it doesn’t stick to the pot. Add more broth to thin out if desired. You can also use an immersion blender to blend some of the soup a bit. I did this, but left it mostly chunky. Add salt and pepper to taste.