In a large saucepan, combine salted water, bay leaves, juniper berries, peppercorns, and quartered onion. Bring to a boil, then reduce heat to maintain a gentle simmer (approximately 85°C / 185°F, not actively boiling). Add the pork knuckles and simmer for 1 hour 30 minutes until the internal temperature reaches 63°C (145°F).
Remove pork knuckles from the water. Cut diagonal lines into the rind to create a diamond pattern. Rub all over with salt and caraway seeds.
Preheat oven to 200°C (392°F). Position the oven rack in the middle and place a drip pan or casserole dish on a lower rack to catch fat. Place the pork knuckles on the middle rack and roast for 1 hour 30 minutes.
After 45 minutes of roasting, turn the pork knuckles over.
Continue roasting for another 45 minutes. For extra crispy rind, turn on the oven broiler during the last 15 minutes.