Place pork in large plastic bag. Combine 1/2 cup of the sherry and 1 tablespoon of the soy sauce; pour over pork, turning to coat. Tie bag. Marinate in refrigerator 1 to 2 hours, turning several times. Remove pork from marinade. Spread honey on plate. Spread sesame seeds in shallow dish. Roll pork in honey, then in sesame seeds. Arrange pork on roasting rack set in roasting pan. Bake at 350°F 25 to 30 minutes or until meat thermometer registers 155°F. Let stand 5 minutes. Slice thinly on the diagonal. Set aside.
Combine remaining 1/3 cup soy sauce, remaining 1 tablespoon dry sherry, the sesame oil, garlic, ginger and onion in small bowl. Place bowl in center of serving platter. Surround the bowl with spinach leaves. Arrange pork slices on top.