Preheat the oven to 400°F.
In a bowl, mix the smoked paprika, oregano, cayenne pepper, brown sugar, minced garlic, salt and vegetable oil. Mix to form a spice paste.
Place the bell peppers, red onions, and drained black beans on the large baking sheet. Toss them with half of the spice paste until evenly coated. Spread them out on the sheet.
Roast the vegetables in the oven for 5-10 minutes, until they start to soften and slightly caramelize.
Remove the pan from the oven and stir the vegetables and beans to ensure even cooking. Place the salmon fillet, skin-side down, on top of the vegetables. Brush the remaining spice paste evenly over the salmon.
Return the pan to the oven and bake for another 18-20 minutes, or until the salmon is cooked through and flakes easily with a fork. The the internal temperature should reach 145°F (63°C) in the thickest part.
Serve the salmon, vegetables, and beans with the avocado-mango salsa on the side. Garnish with lime wedges for squeezing over the top.