How to Make It
In a medium skillet, heat 1 tablespoon of the oil. Add the garlic and cook over moderately high heat until fragrant, about 30 seconds. Add the wine and boil until reduced by half, about 1 minute. Add the chicken stock and boil until reduced by half again, about 1 minute. Remove the skillet from the heat and whisk in the cold butter, 1 tablespoon at a time.
In another medium skillet, heat 3 tablespoons of the oil. Add the shiitake caps and cook over moderate heat, stirring occasionally, until browned, about 5 minutes. Stir in the sesame seeds and cook, stirring frequently, until lightly browned, about 1 minute. Season the shiitake with salt and pepper and remove the skillet from the heat.
On a plate, toss the pumpkin seeds with 1/2 teaspoon of salt and the cayenne. Press the boned side of the trout fillets into the pumpkin seeds to coat.
In a large nonstick skillet, heat the remaining 2 tablespoons of oil. Add the trout fillets, crusted side down, and cook over moderately high heat until browned, about 2 minutes. Turn the fillets and cook until the fish is just white throughout and the skin is crisp, about 3 minutes. Transfer the fillets to plates.
Add the scallions, tomato, cilantro and lime juice to the sauce and rewarm over moderately high heat, stirring; do not let it boil. Spoon the sautéed shiitake and the sauce over the trout and serve.