To prepare the greens, cut away the tough stalks and stems from the collards and discard any leaves that are bruised or yellow. Fill the sink with water and salt (the salt helps to remove any impurities) and wash the collards thoroughly to remove any grit. Repeat 2 or 3 times until the water runs clear. Dry the greens thoroughly. Stack up several leaves and hand-shred them into ribbonlike pieces. Repeat until all the leaves are shredded.
Coat a 6-quart stockpot with the olive oil and place it over medium heat. Add the onion and garlic, stir to coat, and add the ham hocks and bay leaves; cook about 8 minutes. Pack in the greens, pushing them down into the pot; then add the stock, vinegar, sugar, and red pepper flakes. Bring up to a hard boil for 10 minutes, until the greens start to wilt. Turn the greens over with a wooden spoon. Lower to a gentle boil, cover the pot, and cook for 45 minutes. Taste the pot liquor (broth) and check the seasoning, adding seasoned salt to your taste. Cover and cook for 15 more minutes.
Edited: October 15th, 2009