Preheat oven 450 degrees F.
Lightly flour a clean work surface. Knead dough into a ball. Roll dough out into a large rope. Form a large figure-8 with the dough on a baking sheet. Brush with the egg and sprinkle generously with salt. Bake 15 to 20 minutes until risen and nicely browned.
Let cool before serving. Serve with good, spicy mustard.