Preheat oven to 425° F. Place Mann’s Sweet Potato cubes in roasting pan coated with cooking spray; drizzle with 2 tablespoons of oil and sprinkle with ¼ teaspoon of salt, tossing to coat. Bake at 425° F, for 30 minutes or until tender and golden. Transfer potatoes to large shallow bowl or serving platter.
Peel orange with a paring knife, removing white pith; cut orange in half; cut halves into thin slices; add to bowl or platter with Sweet Potatoes.
Combine remaining ¼ teaspoon of salt, marmalade, butter, lemon juice and pepper in a small microwave-safe glass bowl. Microwave on high for 30 seconds or just until butter melts; stir to combine. Drizzle mixture over Mann’s Sweet Potatoes, tossing gently to coat. Sprinkle with scallions.
To prepare tuna, rub 1 tablespoon of preferred blackened seasoning evenly over both sides of a 1-pound tuna steak. Heat a heavy nonstick or cast iron skillet over high heat; coat pan with cooking spray. Add remaining 2 tablespoons of oil. Cook tuna for 3 minutes on each side or to desired degree of doneness. Slice steak and arrange over sweet potatoes mixture.