Preheat the oven to 180C/160C Fan/Gas 4. Line a baking tray with baking paper. Lay the fish on the tray, season with salt and pepper drizzle with oil. Bake for 20-30 minutes, depending on the size of the fish, or until the flesh flakes easily.
Meanwhile, put the beans in a steamer and cook for 5-7 minutes, or until cooked.
Toast the almonds in a hot frying pan for 2-3 minutes. Transfer to a plate. Return the pan to the heat, add the butter and cook until it turns nut-brown. Stir in the lemon juice, toasted almonds and a pinch of salt and pepper, then remove from the heat.
For the salad, put the leaves in a large salad bowl. Put the oil, vinegar and mustard in a small bowl and whisk.
Put the fish on a large serving plate and peel back the skin. Pour the buerre noisette over the fish. Pour the dressing over the salad and mix. Serve the fish with the beans and salad.