In a skillet over medium heat, add olive oil. Once hot, add the ground turkey (or beef) and cook until browned, breaking it apart with a spatula. Drain excess fat if necessary.
Add diced onions, minced garlic, red, and green bell peppers to the skillet. Cook for about 5 minutes, or until the vegetables soften.
Transfer the meat and vegetable mixture to the slow cooker.
Add the diced tomatoes (with their juice), kidney beans, black beans, corn, chili powder, cumin, smoked paprika, cayenne pepper, salt, and pepper to the slow cooker. Stir well to combine all ingredients.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chili thickens and flavors meld together.
Taste the chili and adjust seasoning as desired before serving.
Serve hot, garnished with fresh cilantro, and accompanied by sour cream and shredded cheese if desired.
Notes
Adjust cayenne pepper to taste for desired spiciness.