Step 1Place the ribs in a glass baking dish. Season with pepper and add about 8 sprigs of thyme. Cover with plastic wrap and refrigerate overnight.
Step 2The next day, season the ribs on all sides with salt and bring to room temperature. Brown the ribs in the oil in a Dutch oven or roasting pan over high heat until well browned on all sides, about 4 minutes a side.
Step 3Heat the oven to 350 degrees.
Step 4Remove the ribs to a platter. Cook the onion, celery and carrot in the same pan you've browned the meat in over medium heat, stirring constantly to pick up all the crusty bits left in the pan. Cook until the vegetables are lightly browned, about 6 to 8 minutes. Add the bay leaf, about 6 sprigs of thyme and the parsley.
Step 5Add the vinegar, red wine and Port and reduce by three-quarters; this will take about 15 minutes. Add the veal stock and bring to a boil.
Step 6Place the ribs meat-side down in the pan. The liquid should come 3/4 of the way up the side of the meat. Cover the pan with oven-proof plastic wrap and then foil. Place the ribs in the oven and braise for approximately 3 hours.
Step 7After 2 hours 45 minutes, check the meat for doneness. It should be tender and falling off the bone. Insert a paring knife into a rib; the meat should fall off the knife easily. When the meat is done, uncover the pan and let the ribs brown in the oven, 10 to 15 minutes.
Step 8Let the ribs rest for 1/2 hour in their juices, then remove them to a baking sheet and strain the pan juices into a bowl. When the juices cool you will be able to skim off most of the fat.
Step 9When ready to serve, place the ribs in their juices in a 400-degree oven to reheat, about 15 minutes.
Step 1Boil the baking and Yukon Gold potatoes (skin on) in water to cover with 1 tablespoon of the salt until tender, about 20 minutes. Strain them and set aside until cool enough to handle. Peel the potatoes and put them through a food mill or potato ricer, then place them in a heavy-bottomed pan. Stir the potatoes with a wooden spoon over medium heat to dry them out, then slowly add in the chunks of butter, stirring constantly. Season with the remaining 3/4 teaspoon of salt.
Step 2Meanwhile, heat the milk and cream together in a separate pot.
Step 3When the potatoes have absorbed all the butter, slowly add in the milk mixture until you achieve the consistency of a puree. Taste for seasoning and remove from the stove.
Step 1Mix together the creme fraiche and horseradish. Season with salt and pepper to taste.
Step 1Melt the butter in a skillet over medium heat. Cook the shallots, stirring until softened, 4 to 5 minutes. Rinse the spinach but do not dry, then add it to the pan. Cook the spinach until just barely wilted, about 2 minutes. Season with salt and pepper.
Step 2In the center of each of 8 large bowls, place a spoonful of the hot potato puree. Divide the spinach among the 8 bowls. Place a short rib in the center of each bowl and spoon over some of the braising liquid. Top with a generous spoonful of horseradish cream and serve immediately.