Heat the vegetable oil in a large stock pot over medium heat. Cook and stir the onion in the hot oil until softened and translucent, about 5 minutes. Add the turkey, tomatoes, potatoes, water, ketchup, barbecue sauce, vinegar, Worcestershire sauce, hot pepper sauce, salt, and pepper. Bring stew to a boil; reduce heat to low and simmer for 2 hours, stirring occasionally. Add corn and cook another 30 minutes.