Marinated Pork: In large bowl, combine water, first-listed maple syrup, kosher salt and brown sugar for marinade. Mix well to dissolve sugar and salt. Place pork loin in a deep pan. Cover pork completely with marinade, turning to coat evenly. Cover with plastic wrap. Marinate 8 hours in refrigerator. Drain and discard excess marinate. Remove pork from marinate and place pork in a roasting pan. Season evenly with black pepper and garlic powder. Roast in a 325˚F oven for 2 hours until internal temperature is 155˚F. Remove pork loin from oven. Spread pure maple syrup over top of it. Slice pork loin into 12 slices.
Mango Chutney: Slice mangos into 1 inch cubes. Place all ingredients in sauce pan. Bring to a boil. Reduce heat and simmer for 45 minutes or until jam-like consistency. Stir frequently.
Roasted Red Potatoes: Combine potatoes, garlic, rosemary, olive oil, salt and pepper. Toss to evenly coat. Coat sheet pans with vegetable oil. Place potatoes in a single layer on sheet pan. Do not overcrowd. Roast in a 350˚F oven until fork tender.
Serve sliced pork loin with Roasted Red Potatoes and Mango Chutney.