Preheat your grill to medium-high.
Place the oil in a skillet over medium, to medium-high heat. Add the onions and cook, stirring occasionally, until quite tender, about 5 minutes. Stir in the chili powder and cumin and cook 1 minute more. Stir in the barbecue sauce and stock, and reserve the onions on low heat until the sausages are cooked.
Grill the sausages 4 to 5 minutes per side, or until cooked through. Set one sausage in each of the buns. Top with the onions and enjoy.
Note: Choose your favourite variety of Thrifty Kitchens sausage for this recipe. Varieties in our fresh meats case include Italian, chorizo and beef.