Heat oil in a large skillet over medium-high heat. Add ground turkey and saute, breaking it up as it cooks; about 3 minutes. Stir in onions, peppers, and garlic and cook until the vegetables begin to soften; 2 to 3 minutes. Add the chili powder and ground cumin to the skillet and cook for 1 minute more. Transfer to a 6-quart slow cooker.
Add the rinsed quinoa, salsa, stock, and black beans to the slow cooker; stir to combine. Cover and cook on low for 2 hours and 30 minutes. One hour before the chili has finished cooking, add the corn and cook until tender. Season to taste.
Top quinoa chili with cilantro sprigs, lime, and sour cream if desired.