Heat oil in a saute pan over medium high heat until shimmering. Add ground turkey (or chicken) and saute until browned, breaking up chunks and stirring with a long spoon frequently, about 4-6 minutes. Drain, then add the meat to the bottom of a slow cooker.
Add remaining ingredients (except the toppings) to the slow cooker, and stir to combine. Cover and cook on high heat for 4 hours or until the onions are soft and translucent. Season with salt and pepper if needed. Serve warm with desired toppings.
