Preheat oven to 425°.
Combine first 5 ingredients in a bowl; cut in margarine with a pastry blender or 2 knives until mixture resembles coarse meal. Combine milk and mustard; add to flour mixture. Stir until the flour mixture is moist.
Turn dough out onto a lightly floured surface. Knead 5 or 6 times. Roll dough to about 1/2-inch thickness, and cut with a 1 3/4-inch biscuit cutter. Place on a baking sheet coated with cooking spray. Bake at 425° for 12 to 15 minutes or until lightly browned.