Preheat oven: Preheat oven to 400°F (200°C). Cut a large sheet of parchment paper.
Make miso butter: In a small bowl, mash together ghee (or softened butter), miso paste, and garlic until smooth.
Season fish: Place trout fillet in the center. Pat dry and drizzle with sake, then sprinkle with salt, black pepper, and brown sugar. Spread the miso butter evenly over the top.
Wrap according to thickness:
- For thick steelhead/ rainbow trout (about 1 inch at the thickest part, ~1 lb or larger): Use a candy-wrap style. Bring the parchment up around the fish and twist the ends tightly like a wrapped sweet. This forms a loose tent over the fish, letting a little steam escape so the fillet bakes gently without over-steaming.
- For thin white-flesh trout fillets (smaller, delicate, leaner): Use a fully sealed parchment pouch (classic en papillote). Fold the edges all the way around to trap steam inside. This keeps thinner, leaner fillets moist and prevents them from drying out.
Bake: Place the wrapped fish on a baking sheet and bake for 14–16 minutes (steelhead/rainbow) or 12–14 minutes (thin fillet trout). Look for opaque flesh that flakes easily, with just a faint blush in the middle.
Serve: Carefully open the parchment (watch the steam). Spoon any melted miso butter from the packet over the fish. The skin will be soft rather than crispy — simply flake the fillet away from the skin and enjoy it with the buttery sauce. Finish with lemon juice and scallions. Serve warm.
Notes
Steelhead trout is richer and fattier, so the looser “candy-wrap” method works best. It keeps the texture juicy without over-steaming.
Thinner, leaner trout (white-flesh) benefits from a fully sealed pouch, which locks in steam and keeps the fish moist.
The skin will not turn crispy with this parchment style of baking. The upside is that the fish stays incredibly moist and juicy. For crispy skin, pan-seared trout is a better option (recipe coming soon).
Cooking temperature guide (with carryover heat):
125°F (52°C) – Pull the trout when it hits this temp. Carryover heat will raise it a few degrees as it rests, bringing it closer to 130°F. This leaves the fish moist, tender, and slightly pale pink in the center (chef’s choice).
135–140°F (57–60°C) – After resting, the fish will be closer to 138–142°F. The flesh will be fully opaque, flaky, and still juicy.
145°F (63°C, FDA guideline) – If you bake all the way to this temp, carryover will push it higher. The fish will be completely cooked through but more likely to be on the dry side.
Visual cues: The trout should look opaque on the outside and flake easily with a fork at the thickest part. A faint pale pink in the very center (like salmon) is safe to eat and gives the juiciest results.