Preheat oven to 350°F (180ºC). Core cabbage. Blanch each cabbage in large pot of boiling salted water, 8 to 10 min. or until leaves start to soften. Remove and run under cold water until cool enough to handle.
Working from core end, carefully pull off 6 to 8 leaves (return cabbage head to boiling water for additional 3 to 5 min. when leaves become difficult to pull off). Repeat with second cabbage to get a total of 24 blanched leaves. Trim off and discard coarse middle vein from leaves. Drain leaves on paper towel-lined tray. Set aside. Thinly slice remaining cabbage on heads. Place 1/4 of the sliced cabbage into each of 2 large greased saucepans (with ovenproof lids) or Dutch ovens.
Mix together beef, pork rice, green onions, 1/3 cup (75 mL) parsley, dill, garlic, salt and pepper. To make each roll, place 2 tbsp (30 mL) filling on core end of each cabbage leaf. Fold in sides over filling and roll tightly to enclose filling. Make 24 rolls. Place 12 rolls, seam-side down, on top of sliced cabbage in each saucepan.
In another large saucepan, mix together tomatoes, 4 cups (1 L) water and tomato paste; bring to a boil. Pour half into each saucepan of cabbage rolls to cover. (If cabbage rolls are not covered with tomato mixture, add more water.) Place remaining sliced cabbage over top of rolls. Cover and bake 2 to 2 1/2 hrs. until rice is tender, meat is cooked through and cabbage is softened. Sprinkle with remaining parsley before serving. To make ahead: Cool cabbage rolls and refrigerate in airtight container for up to 3 days. Alternatively, freeze in airtight container for up to 1 month. Reheat from frozen.
You can also use 4 cans (398 mL each) whole tomatoes and chop them before adding.
Freeze in foil containers and reheat for easy entertaining and clean-up.