Preheat your oven to 400°F (200°C). Prepare a large baking sheet with parchment paper for easy cleanup.
In a spacious bowl, combine the baby potatoes and sliced carrots. Drizzle with 2 tablespoons of olive oil, ½ teaspoon of sea salt, ¼ teaspoon of black pepper, and the smoked paprika. Toss thoroughly to coat all vegetables evenly.
Spread the seasoned vegetables in a single layer on the prepared baking sheet. Roast for 20 minutes, allowing them to begin tenderizing.
While the vegetables roast, pat the haddock fillets dry with paper towels. In a small bowl, whisk together the remaining 1 tablespoon of olive oil, minced garlic, lemon zest, ¼ teaspoon of sea salt, and ¼ teaspoon of black pepper.
After 20 minutes, remove the baking sheet from the oven. Gently push the vegetables to one side, creating space for the fish. Place the haddock fillets on the empty side of the baking sheet.
Spoon the lemon-garlic mixture over each haddock fillet. Return the baking sheet to the oven and continue roasting for another 12-15 minutes, or until the fish is opaque and flakes easily with a fork, and the vegetables are tender.
Once cooked, remove the sheet from the oven. Squeeze fresh lemon juice over the entire dish. Sprinkle generously with chopped fresh dill and parsley before serving immediately.