How to Make It
Preheat the oven to 350°. Spread the walnuts in a pie plate and toast until fragrant and golden, about 7 minutes. Let cool slightly, then break into small pieces.
In a large bowl, whisk the vinegar with the mustard. Slowly whisk in the olive oil and walnut oil and season with salt and pepper. Add the celery, parsley, dill, currants and trout and toss gently. Add the walnuts, toss gently and serve.