1. Remove core from cabbage. Place trivet into multicooker pot; add ½ cup water. Place cabbage core-side down on trivet. Close lid and seal following manufacturer's instructions. Cook on HIGH 6 minutes. Quick release steam, then drain and transfer cabbage to cutting board to cool.
2. Meanwhile, halve onion, then chop one-half onion finely. Shred carrot, celery, and remaining half onion (about ¼ cup each). Chop thyme.
3. Combine in large bowl: chopped onions, tomatoes, vinegar, sugar, raisins, 2 teaspoons garlic, and 2 teaspoons seasoning. Peel large whole leaves from cabbage (about 16); remove tough centers from leaves. Chop remaining cabbage into 1-inch pieces (about 1 ½ cups) and add to tomato mixture.
4. Combine in medium bowl: meatloaf blend, egg, rice, carrots, celery, shredded onions, pepper, and remaining 1 tablespoon minced garlic and 1 teaspoon seasoning; mix until thoroughly blended. Arrange cabbage leaves on flat work surface; place about ⅓ cup meat mixture in center of each leaf. Starting at the stem-end, fold sides in and roll up cabbage leaves around filling (wash hands).
5. Place trivet into multicooker pot; add 1 cup tomato mixture and remaining ½ cup water. Arrange 6 cabbage rolls seam-side down in pot; add about 1 ½ cups tomato mixture. Repeat layers with remaining rolls and tomato mixture.
6. Close lid and seal following manufacturer's instructions. Cook on STEAM 20 minutes or until rolls are 160°F. Let pressure release naturally 10 minutes, then release remaining pressure carefully. Serve drizzled with additional vinegar, if using.

Chef's Tip: You can also core cabbage and place core-side down in large, microwave-safe bowl. Add ¼ cup water, cover, and cook on HIGH 6–7 minutes until tender. Let stand 5 minutes to cool.