Preheat the oven to 400° and cook the rice according to the package instructions. Next, Cut the top of the peppers on the stem end to remove top of pepper. Remove seeds and membranes; rinse peppers. If necessary, cut thin slice from bottom of each pepper so they stand up straight. p

In a large pot, add enough water to cover peppers. Heat to boiling; add peppers. Cook about 2 minutes; drain.

Add the beef and sausage to a large skillet and cook, breaking it up with a wooden spoon, until it is well browned and no longer pink. Drain excess grease.

Return the beef to the skillet and stir in the cooked rice and diced tomatoes. Add the oregano, then salt and pepper to taste. Simmer until the sauce begins to thicken, about 5 minutes.

Arrange the peppers in a flat-bottomed 9×13 baking dish, cut sides up. Spoon the filling into the peppers, dividing evenly and mounding slightly if necessary. Top with cheese, then cover the dish tightly with foil.

Bake 10 minutes covered and then uncover and bake about 10 minutes more, or until the cheese is bubbly and starting to brown.