Preheat your oven to 375°F (190°C) or heat a grill or pan on medium-high.
Pat the whiting fish fillets dry with paper towels to remove excess moisture.
In a small bowl, mix the olive oil, minced garlic, sea salt, black pepper, and optional chili flakes.
Place the fish fillets on a baking sheet (if baking) or in a pan (if pan-searing).
Brush both sides of the fish fillets with the olive oil mixture.
Place lemon slices on top of the fish fillets.
If baking, place the baking sheet in the oven and bake for 12-15 minutes, or until the fish is opaque and flakes easily with a fork.
If grilling or pan-searing, cook the fillets for about 3-4 minutes per side, depending on thickness, until the fish is cooked through.
Remove the fish from heat and garnish with freshly chopped parsley and lemon zest (if using).
Serve the whiting fish immediately with your choice of sides, such as roasted vegetables or a light salad.