How to Make It
Preheat the oven to 350°. Bake the hazelnuts in a pie plate for 12 minutes, until the skins blister. Let cool, then transfer the nuts to a clean kitchen towel and rub together to remove the skins. Coarsely chop the nuts.
Preheat a grill pan. Toss the cucumbers with oil and season with salt and pepper. Working in 2 batches, grill over high heat, turning once, until lightly charred, 3 minutes.
In a bowl, mash the garlic and anchovy to a paste using the back of a spoon. Add the vinegar, dill and sugar and whisk in the 2 tablespoons of oil. Season with salt and pepper, add the grilled cucumbers and let stand until cool. Add the trout, mesclun and hazelnuts, toss well and serve right away.