How to Make It
In a bowl, soak the shiitakes in the tamari-spiked boiling water until softened, about 30 minutes. Drain the mushrooms, reserving 2 tablespoons of the liquid. In a food processor, pulse the mushrooms and the reserved mushroom liquid with the parsley, garlic and shallot until finely chopped. With the machine on, slowly add 1 tablespoon of the oil. Transfer the pesto to a small bowl and season with salt and pepper.
Place the trout on a work surface. Using tweezers, remove the fine pin bones that run along the center of each fillet. Coat a large nonstick baking sheet with cooking spray. Arrange the trout, skin side down, on the sheet.
Heat the remaining 1 teaspoon of oil in a skillet. Add the leeks and cook over moderately high heat until just wilted, about 3 minutes. Add the wine, season with salt and pepper and cook until the liquid has evaporated, 1 to 3 minutes.
Preheat the oven to 400°. Sprinkle the trout with the lemon juice and season with salt and pepper. Spread one-quarter of the pesto in a thin layer on each trout. Spoon the leeks on top and bake for about 10 minutes, or just until the trout is cooked through.