To cook on the stovetop: Use a slotted spoon to transfer the beef to a bowl when it is browned on the outside but not cooked through. To the oil in the pan, add onions and garlic and cook until soft, about 5 minutes. Add carrots, celery, tomato, barley, stock, water, thyme, bay leaf and pepper. Bring to a boil, then reduce heat to simmer, just barely bubbling. Cook for 30 minutes, and test the barley to see if it’s tender. If necessary, simmer for another 10 minutes.