MIX all ingredients except meat and stock until well blended. Coat meat with mustard mixture. Refrigerate 24 hours. Place on racks in roasting pans. Pour stock into pan; cover.
BAKE in 300ºF-standard oven 4-1/2 hours or until fork-tender. Uncover; increase temperature to 400ºF. Bake 20 to 30 min. or until browned. Let stand at room temperature 1 hour. Strain pan juices; skim fat. Shred meat. Pour juices over meat. Keep warm until ready to serve.
CREAMY Dijon Mustard Sauce: Whisk hot water and dry mustard until well blended. Stir in all remaining ingredients except oil. Gradually whisk in oil until well blended. Refrigerate until ready to use.
CRISPY Fried Sweet Onions: Sprinkle onions lightly with salt; spread onto paper towels. Let stand 1 hour. Separate onions into rings; toss with 1/3 cup flour (or with about 1 -1/2 Tbsp. flour for trial recipe). Whisk cornstarch, remaining flour and club soda until well blended. Set aside.
GARLIC-CHILI Braised Mustard Greens: Saute chipotle peppers in hot oil in skillet until lightly toasted. Add bacon and water; cook and stir on medium heat 5 min. or until some of the water is evaporated and bacon is partially cooked. Add shallots, garlic and jalapeno peppers; cook and stir 3 to 5 min. or until tender. Stir in remaining ingredients; cook 5 to 10 min. or until greens are wilted. Keep warm until ready to use.
FOR each serving: Dip 4 onion rings in batter. Cook in 350ºF-deep fryer until golden brown; season with salt.
SPREAD 2 Tbsp. Creamy Dijon Mustard Sauce onto cut sides of 1 roll; fill with 1 cup pork, heaping 1/3 cup Garlic-Chili Braised Mustard Greens, 2 tsp. pine nuts and 1/4 cup cheese.
BAKE in 350ºF-standard oven 3 to 5 min. or until cheese is melted and sandwich is heated through. Fill sandwich with 4 Fried Sweet Onions and 1 tsp. parsley.