Heat oil in stock pot over medium heat. Saute garlic, onions and peppers until softened, about 3-6 minutes. Add cumin, chili powder, cayenne and oregano, stir to combine and cook for 1-2 minutes to lightly toast spices.
Add crushed tomato, water and red lentils and bring to a boil. Turn heat to a simmer, place lid on pot leaving it slightly ajar and cook for 20 minutes until lentils are soft. Add sweet potato, stir and continue cooking for 20-30 minutes until sweet potato are cooked through.
Add salt, lime juice and scallions. Adjust seasonings as desired. Serve with your choice of toppings