In large skillet, heat oil over medium-high heat. Add onion and cook until softened, about 5 minutes. Add ground turkey, and break up with a fork. Stir in carrot and garlic, and continue cooking until meat is cooked through, about 8 minutes. Stir in water, tomato paste, chili powder, and salt. Heat to boiling, stirring constantly. Reduce heat to low, and simmer 15 minutes.
Meanwhile, cut top off hot potatoes and scoop out some of the flesh. Spoon taco mixture into potatoes, and top with cheese, lettuce, and tomato.