Core cabbage head. Cook cabbage, stem side down, in boiling water to cover just until outer leaves separate easily from head without tearing. Reserve 12 large leaves for rolls (refrigerate remaining cabbage for another use). Trim the thick vein from the bottom of each leaf, making a V-shaped cut. , In a large bowl, combine rice, onion, egg, milk, salt and pepper. Add beef, mix lightly but thoroughly. Place about 1/4 beef mixture on each leaf. Pull together cut edges of leaf to overlap; fold over filling. Fold in sides and roll up. , Place trivet insert and 1/2 cup water in a 6-qt. electric pressure cooker. Set 6 rolls on trivet, seam side down. In a bowl, mix tomato sauce, brown sugar, lemon juice and Worcestershire sauce; pour half the sauce over cabbage rolls. Top with remaining rolls and sauce. , Lock lid; close pressure-release valve. Adjust to pressure-cook on high for 15 minutes. Quick-release pressure. A thermometer inserted in beef should read at least 160°., Remove rolls to a serving platter; keep warm. Remove trivet. In a small bowl, mix cornstarch and remaining 2 tablespoons water until smooth; stir into pressure cooker. Select saute setting and adjust for low heat. Simmer, stirring constantly, until thickened, 1-2 minutes. Serve with rolls.