In a cast-iron skillet, add 1 tablespoon vegetable oil and cook the onion (1 cup), bell pepper (1), and garlic (4) until they are soft, or for about 7 minutes. Add the beef (24 ounces) and cook until it is no longer pink. Remove any excess fat. Add the rest of the filling ingredients and simmer uncovered over medium-low heat, or until most of the liquid has evaporated, about 20 minutes.
Make the topping
In a medium mixing bowl, whisk all the topping ingredients together. Drop the corn topping over the filling and then spread it out evenly. Loosely tent top of the skillet with aluminum foil.
Bake the pie in a preheated oven for 25 minutes. Remove the foil and continue to cook for another 15 minutes.