01 - Preheat oven to 400°F. Lightly grease a baking dish capable of holding fillets in a single layer.
02 - Pat haddock fillets dry with paper towels and arrange evenly in the prepared baking dish.
03 - In a small bowl, whisk together olive oil, lemon zest, lemon juice, capers, minced garlic, sea salt, black pepper, parsley, and dill if using.
04 - Spoon the marinade evenly over the haddock, coating each fillet thoroughly.
05 - Bake uncovered for 15 to 20 minutes until fish is opaque and flakes easily with a fork.
06 - Remove from oven, garnish with lemon slices and extra parsley, then serve immediately.