Preheat the oven to 400F/200C. Line a baking sheet with parchment paper. Add the green beans and fish to the baking sheet. Drizzle with olive oil and sprinkle with salt and pepper. Bake for 15 minutes, or until fish is cooked through.

For the romesco sauce, in a food processor or high-speed blender, add all of the ingredients except for the olive oil. Pulse until finely ground, then, with the blender or processor on, slowly drizzle in the olive oil until smooth. If too thick, thin out with some water. Add salt and pepper, to taste.

Serve fish and green beans topped with romesco sauce.