Mash barley to a grits-like texture. Bring broth to a boil, and add barley grits. Cook on medium heat, stirring contstantly until broth is absorbed and polenta is hot. Stir in margarine.
Transfer to a greased baking dish and bake for 15 minutes. Slice and serve with gravy.
Alternate serving method: Skip the baking step, and serve barley grits right from the pot, as you would grits or mashed potatoes.