In a deep, 12-inch nonstick frying pan or 4- to 5-quart pan, combine onion, olive oil, chili powder, cumin, and salt and pepper to taste over medium-high heat.
Stir often until onion begins to soften and spices are fragrant, 3-4 minutes.
Add turkey and garlic to pan.
Cook, stirring often and crumbling meat, until turkey is lightly browned, about 4 minutes.
Add beans and broth.
Bring to a boil over high heat, then reduce heat and simmer just until heated through,2-3 minutes.
Spoon chili into serving bowls.
Offer cheese, sour cream, and green onions to add to taste.