Peel the potatoes and onion, slice them into rounds about 1/2 inch thick, and place them in a lightly oiled oven-safe dish. Sprinkle with a pinch of salt and pepper.

Place the walnuts in a mortar and lightly crush them. Add the garlic-parsley mixture, ñora pepper paste, a couple of tablespoons of olive oil, the wine, and a pinch of salt. Mix well.

Season the monkfish with salt and pepper, place it on top of the potatoes and onion, and pour the walnut mixture over everything.

Cover with aluminum foil and, with the oven preheated to 430°F (220°C) on both top and bottom heat, bake for 20 minutes.

Uncover and bake for another 10 minutes at 465°F (240°C). Plate and serve.