- Preheat the oven to 180 ºC.
- Cut the saithe into chunks and slice the cherry tomatoes in half and set aside.
- Peel and cut the potatoes into thin slices. Place the potatoes in an ovenproof dish, season with salt and pepper, drizzle with a little olive oil and bake for about fifteen minutes.
- Chop the mushrooms and then finely chop the garlic, basil, and thyme.
- Lightly saute the mushrooms and garlic in a little olive oil for 1-2 minutes, then add the thyme and season with salt and pepper. Add this mixture to the ovenproof dish with the potatoes, sprinkle with basil, salt, and pepper, and add the fish. Place the sliced tomatoes and sundried tomatoes around the fish, and bake again until the fish is cooked, for about 15 minutes.
- For the sauce, chop the parsley, mint and garlic, place in a bowl together with the olive oil, mustard, and capers, and mix and whisk together until a thick sauce is obtained.
- Serve the saithe and potatoes with the sauce on the side.