Core the heads of cabbage and place them in the pressure cooker, core side down, along with enough water to cover the bottom of the pressure cooker by an inch. Pressure cooker on HIGH for 2 minutes. Reduce the pressure with the QUICK-RELEASE method and carefully remove the lid. Let the cabbage cool on a towel for a minute and then carefully remove the outer leaves of the cabbage, trying not to tear them. You should get at least 6 good leaves from each head of cabbage. Remove the thick vein from each leaf and discard. Shred half of one of the remaining cabbages. Use the rest of the cabbage for another use, like coleslaw.

Combine the shallot, garlic, pork, beef, rice, tomato paste, parsley, salt and pepper in a bowl and mix together gently. Shape the mixture into twelve small logs and wrap each log in a cabbage leaf, starting at the top of the leaf and folding in the sides.

Pre-heat the pressure cooker using the BROWN setting.

Add the onion and shredded cabbage to the cooker and cook for a minute or two. Add the tomatoes, tomato purée, vinegar brown sugar, salt and pepper. Nestle the cabbage rolls into the sauce, cover and lock the lid in place.

Pressure cook on HIGH for 6 minutes.

Let the pressure drop NATURALLY and carefully remove the lid. Transfer the cabbage rolls to a resting plate. Season the tomato sauce to taste with salt and pepper and pool onto a serving plate, top with the cabbage rolls, sprinkle with parsley and serve.