1. Have pork boned, but kept intact. Wipe clean with a damp cloth; dry with paper toweling; then rub with salt and refrigerate, covered, 2 days.
2. Wipe pork with a damp cloth to remove excess salt. Place in a heavy pan with water. Bring to a boil; then simmer, covered, until tender (about 1 1/2 hours), turning meat several times. Drain, reserving liquid for stock.
3. Squeeze pork snugly into a deep rectangular pan (like a cake pan) and cover with a weighted tray. (Use heavy books or a kettle filled with water for the weight.) Let stand until meat is compressed and rectangular (about 2 to 3 hours).
4. Remove weights and refrigerate pork to chill. Slice 1/4 inch thick, then in rectangles 1 1/2 inches wide and 2 inches long.