Bacon adds a smoky flavor to this earthy soup; tomato paste adds a touch of sweetness. Use quick-cooking barley as a time-saver. It has the same nutty flavor as pearl barley, but it cooks in approximately half the time.
Although it makes a delightful breakfast, the frittata could also be served with a green salad for a lunch or light dinner. White button mushrooms can be substituted for the shiitakes; trim but do not remove the stems.
Cook the vegetables, then add the seasoned eggs, and bake the frittata -- all in one pan.