Preheat oven to 400°F.
Rinse the fish with cold water, and pat dry with paper towel.
Line a baking sheet with foil, coat with olive oil, or spray, then arrange the haddock fillets and season with salt and pepper.
In a small bowl, whisk together melted butter, lemon juice, garlic, parsley and tarragon. Pour over the haddock fillets.
Bake for 15 minutes, and the last 5 minutes, place the fillets under the boiler to create a crispy surface. The fish should be flaky and tender when cooked. Squeeze lemon over the haddock before serving.
Serve immediately with roasted potatoes, asparagus and cherry tomatoes.