- Preheat oven to 375-degrees.
- Place fish in baking dish. Whisk together wine & mustard and pour over fish. Sprinkle with salt, white pepper, and fresh thyme. Cover fish with wild leeks , morels, and fiddleheads. Cover loosely and bake for 20 minutes.
- Carefully remove fish and keep warm.
- Pour fishing liquid into saucepan and heat on high. Reduce heat and whisk in butter. Add remaining fiddleheads and chive blossoms. Cook 1 minute.
- Arrange fish on hot serving dish. Pour rich sauce over fish.