Remove core from cabbage, leaving cabbage whole and intact. In a large pot of boiling water, add head of cabbage and boil for 8 minutes, turning a few times. Carefully remove head of cabbage and rinse under cold water. Gently remove 6 leaves, being careful not to rip any. Return head of cabbage to pot of boiling water and boil for a further 8 minutes. Carefully transfer pot to sink and carefully pour out boiling water, then refill pot with cold water. Gently pull 6 more cabbage leaves from head. Pat leaves dry with paper towel and set aside.
Preheat oven to 375°F (190°C). Pour 2 cups tomato sauce onto bottom of a 13 x 9-inch (2 L) baking dish. Set aside.
Boil ½ cup (125 mL) water in a large skillet over high heat. Add mixed vegetables, corn and peas; cook for 2 minutes. Drain in a colander and set aside. Return empty skillet to stove. Heat oil on medium-high heat and sauté beef with onion, garlic, cumin, oregano, paprika, salt and pepper for 8 to 10 minutes, or until beef is cooked through and starting to brown. Cool slightly.
Stir cooked vegetables, brown rice, egg and 3 tbsp (45 mL) parsley into the beef mixture. Place ? cup (75 mL) of the mixture into centre of each cabbage leaf. Bring the bottom (stem) end up and over the filling and fold each side in before rolling up to the top of the leaf. Place each cabbage roll, seam side down, into prepared dish. Top with remaining tomato sauce.
Bake covered for 45 minutes. Remove cover and bake an additional 10-15 minutes, or until cabbage is tender and sauce is bubbling. Sprinkle with remaining parsley before serving.
Tip: Substitute ground beef with ground chicken, turkey, pork or crumbled firm tofu.