How to Make It
Preheat the oven to 300°. In a large enameled cast-iron casserole, combine the ham hocks, stock, 2 cups of the water, the onion, celery and peppercorns and bring to a boil. Cover and braise in the oven for about 2 hours, or until the meat begins to fall off the bones. Remove the hocks and let cool, then remove the meat and shred it. Reserve 2 tablespoons of the braising liquid. Turn the oven up to 350°.
In a bowl, combine the egg yolks, egg white, pickled okra brine, 1 tablespoon of the liquid and the remaining 1 tablespoon of water. Whisk in the vegetable oil and mustard, then fold in the okra and chives. Season the gribiche sauce with salt and pepper.
On a lightly oiled baking sheet, toss the potatoes with 1 tablespoon of the olive oil and the cheese and season with salt and pepper. Spread in a single layer and bake for 20 minutes, or until tender and lightly browned. Keep warm.
In a small bowl, toss the watercress with the remaining 1 teaspoon of olive oil and the lemon juice. In a medium skillet, heat the remaining 1 tablespoon of braising liquid. Add the ham and stir until warmed through. Transfer to a medium bowl and fold in 1/4 cup of the gribiche sauce. Pack 1/2 cup of the ham into a 3-inch ring mold in the center of each dinner plate, then lift off the mold. Arrange the watercress salad on one side and the potatoes on the other and serve.