A variation on the classic French pommes dauphinoise. You might need some salad leaves, perhaps arugula or baby spinach, to wipe up the mustardy, smoky cream from your plate. Amazing Seafood Recipes
Preheat the oven to 375°. In an 8-by-10-inch gratin dish, gently toss the potatoes with the mackerel and bay leaves. In a bowl, mix the cream with the mustard and season with salt and pepper. Pour the cream over the potatoes and bake for about 1 hour, or until the cream has thickened and the potatoes are golden and tender. Discard the bay leaves before serving.
A not-too-fruity, slightly assertive white, such as an Alsace Pinot Blanc, balances the pungent, smoky flavors of the mackerel.