For the ham hock gravy: Combine the ham hocks, corn and ice water in a pot. Bring to a boil, then reduce to a simmer and cook for 3 1/2 hours. Add the celery, carrots and onions, and cook for another 30 minutes.
Strain the stock, reserving the ham hocks. When cool enough to handle, pick the meat off of the ham hocks.
In a 4-quart pot, melt the butter and stir in the flour. Cook the roux for 2 minutes, then stir in 2 quarts of the ham hock broth, followed by half of the picked ham hock meat. Simmer the gravy for 15 to 20 minutes. Season with salt and pepper. (Reserve 8 cups of the ham hock broth and half of the picked ham hock meat for the collard greens.)
For the collard greens: Melt the butter in a large pot. Add the onions and garlic, and saute for 3 to 4 minutes to sweat the onions. Add the chile flakes and saute 1 minute. Add the collard greens and ham hock meat, and stir to wilt the collards. Add the cider vinegar, apple juice and 8 cups of the ham hock broth. Bring to a simmer, cover the pot, and simmer until the greens are tender, 1 hour. Season with salt and pepper.
For the roasted sweet potatoes: Preheat the oven to 450 degrees F.
Toss the diced sweet potatoes in a bowl with the grapeseed oil, salt and pepper.
Spread the sweet potatoes out on a baking sheet and roast in the oven until tender and browned, 15 to 20 minutes.
Transfer the sweet potatoes to a saute pan. Add the molasses, chili powder and cayenne. Saute over high heat, tossing to coat the sweet potatoes. Season with salt and pepper.
For the pork chops: Preheat a grill or grill pan to high.
Sprinkle the pork chops with the salt and pepper. Grill until cooked through and nicely marked, 2 to 3 minutes per side. Remove the chops from the grill and plate immediately.
For plating: Divide the sweet potatoes between six plates. Using a slotted spoon, strain the collard greens and plate them next to the sweet potatoes. Shingle the pork chops over one side of the sides. Smother with ham hock gravy. Serve.