Preheat the oven to 425 degrees . Using a food processor, chop the almonds; transfer to a bowl. Add the bread to the food processor and process into coarse crumbs; combine with the almonds.
In a skillet, heat the olive oil over medium-high heat. Add the onion and garlic and cook until softened, about 5 minutes. Stir into the bread mixture, along with the currants, parsley and lemon peel; season with salt and pepper.
Working on a parchment-paper-lined baking sheet, open the trout like a book and season with salt and pepper. Divide the stuffing among the trout and fold to enclose. Bake until the fish is opaque at the thickest part, about 15 minutes.