In 10-inch skillet over medium heat, melt one tablespoon of margarine. Cook mushrooms and onion until tender. In a small bowl beat egg whites slightly, add kasha and stir until grains are well coated. Push vegetables to one side of skillet. Add the remaining margarine. Cook kasha for 2 minutes until grains become separated and dry. Stir constantly. Stir in boiling water, salt and bullion cube. Bring to a boil over high heat. Reduce heat to low, cover and simmer for 10-12 minutes until kasha is tender. Cook Manischewitz® Egg or Yolk Free Bow Ties according to package directions. Drain pasta and add to skillet. Mix bow ties with kasha and vegetables.