Peel the sweet potato and cut it into small, half-inch cubes for quick cooking.
Heat the olive oil in a medium pot over medium heat, then add the diced red onion and green bell pepper.
Sauté the vegetables for 3-4 minutes until they begin to soften.
Add the ground turkey to the pot, breaking it up with a spoon, and cook until no longer pink.
Stir in the chili powder, cumin, garlic powder, sea salt, and black pepper to toast the spices for 1 minute.
Add the diced sweet potato, black beans, tomato puree, and water to the pot.
Bring the mixture to a boil, then reduce the heat to low and cover with a lid.
Simmer for 15-20 minutes, or until the sweet potatoes are fork-tender and the chili has thickened.
Transfer the chili to a bowl and top with a dollop of non-fat Greek yogurt before serving.