Start by mixing this magical marinade. In a bowl, combine the miso paste, sake, sweet mirin, caster sugar, and grated ginger. Stir until you have a smooth mixture. The aroma will captivate you; it's like a warm embrace.

Using a shallow dish, coat the black cod fillets generously with the marinade. Make sure every inch is covered; this is crucial for maximum flavor. Cover the dish and refrigerate for at least 12 hours. Some may leave it for as long as 24 hours to intensify the taste. Trust me; patience is key.

When you're ready to cook, preheat your oven to 400°F (200°C). This temperature is perfect for roasting the fish, allowing it to caramelize beautifully without losing moisture.

Remove the cod from the marinade and wipe off any excess. You want the fish to be coated but not drowning in marinade—it ensures a better texture when cooked.

Place the fillets on a lined baking sheet. Drizzle sesame oil over them, and sprinkle a little sea salt. Bake for about 15 to 20 minutes, or until the fish flakes easily with a fork. Chef’s tip: a bit of char is delicious, so don't hesitate to let it caramelize slightly!

Once cooked, plate the fish elegantly. A sprinkle of sesame seeds or fresh herbs can add a vibrant touch. Enjoy this alongside your cucumber salad or steamed rice for a complete meal that shines on any table.