In large saucepan, mix diced tomatoes, Puree, paste, brown sugar, 1/2 teaspoons salt, Worcestershire sauce and allspice. Heat to boiling. Reduce heat. Cover and simmer for 15-20 minutes.
While this is simmering, remove and discard the tough outer leaves from cabbage. Remove 2 large leaves and set aside for later -- Cut out stem of cabbage with a paring knife; Scrape out a cavity in the center of cabbage, leaving 1″ shell.
(I do this with an old ice cream scoop that I've sharpened).
Dice up the cabbage you've removed.
In another large saucepan, cook ground venison, onion, garlic, salt, pepper flakes and black pepper and 1 cup of diced cabbage until meat is browned and cabbage is tender, about 15 minutes.
(I usually save the rest of the diced cabbage for another use).
Drain off fat if you want to, and return to the pan.
Stir in cooked rice and about 1/3 of the Sauce mixture. Remove from heat and.
Fill cabbage shell with the meat mixture.
Place the cabbage, hole-side-up, into a Dutch Oven or Slow-Cooker. Cover the hole with the two reserved leaves.
Ladle half of the remaining sauce / cabbage mixture over and around the stuffed cabbage.
If using a Dutch Oven; Bring this to the boil over high heat. As soon as it starts to boil, Reduce heat to Low. Cover and simmer until cabbage is tender, about 1 1/2 hours.
If using a slow cooker; Set temperature to high for 30 minutes, then reduce to low setting and cook for 2-2 1/2 hours, or until cabbage is cooked thru.
To serve: place cabbage in a deep platter, Cut in wedges.
Spoon on some of the remaining sauce over each wedge.