For the ribs and rub: Tear two sheets of aluminum foil (large enough to fully wrap each rack of ribs) and place each on a rimmed baking sheet. Place a rack of ribs on top of each. Mix together the dark brown sugar, chili powder, curry powder, salt, garlic powder, onion powder, black pepper and cayenne in a bowl. Reserve 1 tablespoon rub mixture. Evenly divide the remaining rub between the two racks of ribs and cover all surfaces of the fronts, backs and sides of each. Wrap tightly in the aluminum foil. Refrigerate for at least 4 hours and up to overnight.
Preheat the oven to 500 degrees F.
Bake the ribs 20 to 30 minutes. Reduce the heat to 250 degrees F. Continue to cook until the meat is tender, about 1 1/2 hours.
For the sauce: In a medium saucepan over medium heat, heat the olive oil. Add the onion and saute until translucent, about 5 minutes. Stir in the ginger and the reserved spice rub and saute an additional minute to allow the spices to bloom. Add the ketchup, chicken broth, dark brown sugar, tamarind paste, Worcestershire sauce and garlic powder, and stir to combine. Reduce heat to a simmer and cook until slightly thickened, about 10 minutes.
Remove the ribs from the oven and preheat the broiler to high.
Remove the ribs from the foil and place them on the baking sheets. Spoon 3 tablespoons of the liquid that has gathered in the foil into the sauce and stir to combine. Brush the ribs generously with a few tablespoons of the sauce. Place under the broiler, rotating the baking sheet if necessary, until the sauce begins to brown and thicken, 3 to 4 minutes. Repeat with the remaining ribs. Transfer the ribs to a cutting board and brush with the sauce once again. Serve the ribs with additional sauce and the Slaw.
For the dressing: In a small bowl, whisk together the lime juice, oil, vinegar, granulated sugar, ginger, salt, garlic and black pepper until emulsified.
For the slaw: In a large salad bowl, combine the kale, cabbage, mango, bell pepper, scallions, chile, peanuts, cilantro and mint.