In a bowl, combine the egg, half of the tomato sauce, bread crumbs, onion and green pepper if desired, 1/2 teaspoon of oregano, salt and pepper.
Add beef; mix well.
On a large piece of heavy-duty foil, pat meat mixture into a 14-in. x 8-in. rectangle.
Sprinkle cheeses to within 1/2 in. of edges.
Roll up, jelly-roll style, starting with a short side and peeling foil away while rolling. Seal seam and ends.
Transfer to a microwave-safe glass 9-in. x 5-in. loaf pan.
Microwave, uncovered, at 50% power for 9 minutes, rotating a half turn once; drain. Continue cooking on 50% power for 14-16 minutes or until meat is no longer pink, rotating a half turn once. In a bowl, combine the remaining tomato sauce and oregano.
Pour over meat loaf. Microwave, uncovered, on high for 1-1/2 minutes. Cover loosely with foil; let stand 5 minutes before serving.
