Trim excess fat from flank steak; pound to 1/8-inch thickness using a meat mallet, and set aside.
Combine salt, pepper, and ginger; rub 1 teaspoon mixture into flank steak. Combine remaining salt mixture, onion, and ground meat; mix well.
Place thinly sliced beef evenly over flank steak. Top with pork steaks. Spread ground meat mixture evenly over pork. Roll up jellyroll fashion, and secure with wooden picks. Wrap in cheesecloth, tying ends securely.
Place meat roll in a large Dutch oven. Add water to cover. Bring to a boil. Reduce heat; cover and simmer 1 1/2 to 2 hours. Remove meat roll from water; press between 2 plates. Weight down for 2 hours to press out moisture. Remove and discard cheesecloth and wooden picks. Refrigerate meat roll until well chilled; cut into thin slices, and serve cold.