Heat the oven to 400°F and grease a 9-by-13-inch baking dish.
Brown the beef, peppers and onion in a large skillet over medium-high heat for 8 to 10 minutes, until the beef reaches 160°F, then drain the excess fat.
Stir in the tomatoes, Worcestershire, oregano, 1/2 teaspoon salt and pepper and spread the filling in the baking dish.
Whisk the cornmeal, flour, baking powder and remaining salt together in a medium bowl.
Whisk the milk, egg and melted butter in a second bowl, then fold the wet mixture into the dry just until no flour pockets remain.
Spoon the batter over the beef and spread it carefully to the edges without mixing the layers.
Bake for 25 to 30 minutes, until the cornbread is golden and a tester inserted into the topping comes out clean.
Rest for 10 minutes before cutting into squares.