1 For the pesto: Combine all the ingredients for the pesto in a blender. Blitz until smooth and then scrape into a bowl. Season to taste with salt and pepper, and then set aside.
2 For the cod and salad: Preheat the grill to hot. Arrange the cod on a grilling tray and season with salt and pepper. Drizzle with avocado oil and grill for 5 - 7 minutes, turning once, until the flesh is firm yet a little springy to the touch.
3 Remove the cod from the grill and leave to rest briefly.
4 Arrange the tomatoes, radish, onion, peppers, and lettuce on plates, leaving a space in the middle.
5 Sit the cod in the middle and spoon over the pesto before serving.