Thaw peaches slightly; dice and set aside. Whisk together the marmalade, lemon juice, ginger, ground mustard, cinnamon and soy sauce; stir in peaches.
Place pork into a large zip lock bag or glass dish and pour in the peach marinade. Allow pork to rest in marinade for at least 15 minutes, and up to overnight. Turn the pork at least once, halfway through the marinating time.
Preheat oven to 375 degrees F. Place pork into a clean baking dish; discard the marinade. Bake for 20-45 minutes, or until the pork is no longer pink and the juices run clear.
While pork is in the oven, cook the rice as directed on the package. Heat olive oil in a large skillet over medium. Toss in the asparagus and cook for 3-5 minutes or until slightly tender.
Serve pork with rice, pan-seared asparagus, and cubed watermelon.