Freeze the bacon 25 minutes. Remove and cut the bacon crosswise into 1⁄8-inch pieces.

Fill a sink with cold water. Place a cutting board near the sink. Stack 4 collard green leaves on top of each other. Remove the stems with a sharp knife, and reserve for Pickled Collard Green Stems recipe. Cut the leaves into 2-inch squares. Repeat with remaining collard green leaves, and rinse in cold water. Drain.

Heat the olive oil in a 4-quart stockpot over medium. Add the bacon. Cook until crisp, about 10 minutes. Remove from the heat. Transfer the bacon to paper towels to drain, reserving the drippings in pot. Reserve the bacon pieces for garnish.

Return the pot to medium. Cook the onions and garlic in the hot bacon drippings 2 minutes, stirring often. Add the ham hocks, and cook 5 minutes, turning every 45 seconds or so. Pour 4 cups cold water over the ham hocks, and add the bourbon and vinegar. Bring to a simmer over medium, and cook 25 minutes.

Stir in one-fourth of the collards. Continue adding the collards, one-fourth at a time, stirring after each addition. After all collards have been added, simmer 2 minutes.

Sprinkle the collards with the salt and black pepper, and cook until the greens are tender, 1 hour to 1 hour and 30 minutes. Remove from the heat, and stir in the red pepper flakes. Let stand 30 minutes before serving.

Meanwhile, remove the ham hocks; cool slightly. Pull the meat from the bone. Chop the meat and add it to the collards. Discard the bones. Return the meat to the pot with the greens, and stir. Discard the bones.

To serve, sprinkle the collard greens with the reserved bacon. Garnish with the Pickled Collard Green Stems.