In a skillet over medium heat, heat oil and add ground turkey and cook stirring occasionally until the turkey starts to brown. Add the diced onion and cook for 2 minutes. Add garlic, and cook for 30 seconds. Remove from heat.
Add the ground turkey and onion to the slow cooker, and season with chilli powder, cumin, paprika, salt, and pepper.
Add tomato sauce, diced tomatoes, chicken broth/stock, black beans, kidney beans, and corn. Give everything a good stir, cover with the lid and cook on high for 4 hours or on low for 8 hours.
Serve with toppings: green onions, avocado, shredded cheese, and sour cream or Greek yogurt.