Prep your ingredients. Add the oil and the onion to a pot over medium-high heat. Sauté the onion for 5 minutes.
Add the turkey to the pot, and cook it until it turns white (about 5 mins), breaking it up with your spoon/stirring it periodically.
Add the tomatoes and remaining ingredients except the sour cream and salt & pepper.
Once the chili starts to bubble, reduce the heat so it's gently simmering. Let it cook for about 15-20 minutes, stirring it periodically.
Stir in the sour cream and season with salt & pepper. Serve immediately as-is or with suggested toppings.
Notes
Chili powder is a generally mild blend of spices, but be sure to check yours if heat is a concern. I use mild green chilis, but feel free to use hot ones instead. You could also add some cayenne pepper if you want to kick up the heat.
I found this chili to have plenty of liquid, but if you want a bit more, add in some chicken broth.