In a small saucepan, combine pineapple juice, soy sauce, brown sugar, minced garlic, grated ginger, lemon juice, and red pepper flakes. Heat over medium, whisking occasionally for about 5 minutes until thickened.

Pat the salmon fillets dry with paper towels and brush generously with olive oil. Season with black pepper and a pinch of salt.

Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper, place the salmon skin-side down, and spoon half of the glaze over each fillet.

Bake for about 12-15 minutes until the salmon turns pink and flakes easily, then drizzle with the reserved glaze before serving.