Preheat: Heat oven to 400°F (200°C). Line a baking sheet with parchment or a second layer of foil for easy removal.

Prepare Packets: Tear two 12×12-inch sheets of heavy-duty aluminum foil. Brush the center of each with olive oil to prevent sticking.

Season Fillets: Place a trout fillet skin-side down in each foil piece. Sprinkle with salt and pepper. Top with lemon slices, jalapeño rounds, herbs, and pats of butter.

Seal Foil: Fold long sides over fish, then fold ends into tight seams—creating a sealed packet that traps steam.

Bake: Transfer packets to the prepared sheet and bake 12–15 minutes, until fish flakes easily with a fork.

Rest & Serve: Carefully open packets (steam alert!). Slide fish onto plates, spooning pan juices over top. Garnish with extra herbs or lemon zest.