01 - Preheat oven to 400°F. Lightly grease a baking dish large enough to hold fillets in a single layer.
02 - Dry haddock fillets with paper towels and place them evenly in the prepared baking dish.
03 - In a small bowl, whisk together olive oil, lemon juice, lemon zest, minced garlic, sea salt, and black pepper.
04 - Drizzle the olive oil mixture uniformly over the haddock fillets.
05 - Scatter drained capers and chopped parsley over the fillets.
06 - Bake for 16 to 18 minutes until fish is opaque and flakes easily with a fork.
07 - Serve immediately, garnished with additional parsley and lemon slices if desired.