Heat vegetable oil in a large skillet over medium heat. Add onion, green pepper, yellow pepper, and garlic. Sauté until vegetables are tender.
Stir in turkey and cook until evenly browned. Drain and mix in tomatoes and pumpkin puree.
Season with chili powder, salt, and pepper. Reduce heat to low, cover and simmer for 20 minutes. When ready to serve top each bowl with cheddar cheese and sour cream.
(Makes 6 Servings)