Ox Tongue Pie in Mushroom Sauce

Ox tongue is decadence, fatty and rich. It has none of the mineral tang found in other offal, and when cooked right, it’s all tenderness. Because it’s typically sold whole, you can’t really scale down this recipe, and the amount of labor involved—three days: I’m sorry!—means this is best saved for a party, where it will be the pièce de résistance. Although the dish looks rustic, the techniques that go into it are haute, with the kind of focus on minutiae that we typically associate with Fre