In a large bowl, combine 1 gallon water and 1 cup salt. Add pork tenderloin. Let stand for 1 hour. Remove pork tenderloin, reserving brine. Add pork belly to brine, and let stand for 1 hour.
In a large bowl, combine ground pork, milk powder, mustard seed, garlic, pepper, coriander, sugar, and remaining 1 tablespoon salt. Shape mixture into 16 patties.* Cover and refrigerate until ready to cook.
Preheat oven to 300°.
Place rosemary in a large baking dish. Top with pork belly, fat side up. Roast until tender, about 3 hours. Cut into 20 pieces. Keep warm until ready to serve. Increase oven temperature to 325°.
In large bowl, drizzle beets with 5 tablespoons oil, and season with salt. Wrap individually in foil, and roast until tender. Let cool. Peel, and cut into quarters. Marinate beets in 5 tablespoons oil and sherry vinegar.
In the container of a blender, place half of beets; process until smooth.
In a medium baking dish, combine shallot and 5 tablespoons oil. Season to taste with salt and pepper. Roast until tender, about 10 minutes. Increase oven temperature to 350°.
In a large heatproof sauté pan, heat remaining 7 tablespoons oil over high heat. Sear tenderloin and sausages on all sides. Transfer pan to oven, and bake until a meat thermometer inserted in sausage registers 160° and inserted in thickest portion of tenderloin registers 145°. Cover and let rest for 5 minutes. Divide pork belly, loin, and sausages among serving plates, and serve with roasted shallots. Garnish with beets, beet purée, fennel fronds, chopped parsley, and Sour Cherry Sauce, if desired.
Notes
*To make traditional sausages, you will need 1 hank natural sausage casing. Transfer pork mixture to a pastry bag, and pipe mixture into casing to make 16 sausages. Bring a large pot of water to a boil. Reduce to a simmer, and poach sausages until a meat thermometer registers 165°. Transfer to an ice bath until cool. Sear sausages with tenderloin and bake until warmed.
Recipe by Louisiana Cookin' at https://louisianacookin.com/trio-of-pork/