In a large pot over medium high heat, add oil and ground beef. Cook until no longer pink, about 7-8 minutes.
While beef is cooking, wash and dry all produce. Chop bell pepper, garlic and scallions (separating the white and green parts).
Poke all around the sweet potatoes with a fork. Put on a microwave-safe plate and microwave for 15 minutes.
When meat is cooked, drain grease from pan. Add scallion whites, bell pepper and garlic. Cook until soft, about 5 minutes.
Add the rest of the ingredients to the pot and bring to a boil. Once pot begins to boil, turn heat to low. Cook for 15-20 more minutes. Check the sweet potatoes in the microwave. They are done if you can easily poke them with a fork.
When potatoes are done, make a cut along the top of each potato and open gently. Pour chili over opening of potato, top with a spoonful of Greek yogurt and scallion greens.