Place the cabbage in enough boiling water to cover in a large kettle.
Cook, covered, for 3 minutes or until cabbage is soft enough that individual leaves may be easily removed; pull off the loosened individual leaves.
Cook, covered, for 3 minutes longer and pull off more individual leaves.
Repeat process until all large leaves (about 25) have been removed.
Cut and discard the thick center stem from each leaf.
Chop the remaining, smaller cabbage leaves.
Saute the onion in the vegetable oil in a large skillet for about 5 minutes.
Brown the ground beef with the ground pork in a skillet, stirring until crumbly; drain.
Combine the ground beef mixture, rice, salt and pepper in a large bowl and mix well.
Place about 2 heaping tablespoons of the ground beef filling in the center of each large cabbage leaf.
Tuck the sides of the leaf over the filling, then roll to enclose.
Spread half the chopped cabbage in a Dutch oven or large casserole.
Layer the cabbage rolls over the chopped cabbage.
Cover with the remaining chopped cabbage.
Combine the tomato soup, tomato juice and 1 1/2 cups water in a bowl and whisk until smooth; pour over the cabbage rolls.
Bake, covered, at 350 degrees for 1 1/2 hours.