In a large pot, heat the oil over medium heat. Add in the onion and cook until translucent. Add the garlic and spices and cook for an additional 30-60 seconds.
Pour in the tomatoes, beans, water, pepper, lentils, and tomato paste. Bring to a boil and then lower the heat and simmer for 30 minutes. Stirring every 5-10 minutes so the lentils don't stick to the bottom.
Once the lentils are fully cooked, stir in the brown sugar. Adjust any spices if you like. I've made this mild so it's child friendly.
Serve with tortilla chips, sour cream, and cheese if you like!