1. Heat grill to medium-high. Slice pineapple into 8 rings; pour juice from container into a measuring cup. Add enough pineapple or orange juice to equal 1/3 cup. Set aside.
2. Season beef on all sides with 1/2 tsp of the salt. Coat pineapple and sweet pepper pieces with nonstick cooking spray and season with 1/4 tsp of the salt.
3. In a small saucepan, whisk together pineapple juice, 1/4 cup water, the brown sugar, olive oil, ginger, cornstarch, crushed red pepper, remaining 1/4 tsp salt and the black pepper. Bring to a boil over high heat; simmer 1 minute.
4. Add fillets and pineapple slices to grill, then cover. Grill 3 minutes; uncover, turn over and grill another 3 minutes or until desired doneness. Let beef and pineapple rest 5 minutes. Meanwhile, grill peppers, covered, 5 minutes. Uncover, flip over and grill an additional 3 minutes.
5. Divide pineapple rings among 4 plates. Top each with 3 pepper pieces (one of each color) and a fillet. Drizzle pineapple glaze over beef and serve.