Tripe And Onions

Name: Tripe And Onions
Ingredients: 1 quart milk; 4¼ to 4½ pounds white honeycomb tripe (which comes from the second stomach, the reticulum, of the ox), cut into 1½ by 4½-inch strips; sea salt and freshly ground black pepper; 3 onions , peeled and roughly chopped; 1½ cups all-purpose flour; ¾ cup unsalted butter; a healthy pinch of mace