Prepare the Paper Bag: Fold paper in half, then fold that half in on itself and fold them back on each other to create a canoe shape. Tie each end together.
Layer the Ingredients: Place sliced leek, crushed garlic cloves, slices of lemon, and ginger in the bottom of the bag.
Add the Fish: Place the salmon on top of the layered ingredients. Add a tiny bit of oil, vinegar, and a glug of white wine.
Seal and Cook: Pinch and roll the paper bag to seal it, ensuring no steam can escape. Cook in an oven set to 180°C (356°F) for 15 to 20 minutes.
Prepare the Thai Yellow Curry Broth: Combine coconut milk, onions, shallots, garlic, lemongrass, ginger, and Thai yellow curry paste in a pot.
Serve: Open the paper bag, remove the fish, and place it to one side. Arrange the leeks in a bowl, use the juice from the bag to season the sauce, and peel off the fish skin. Garnish with fennel, sea parsley, and cafe oil.