Heat a large soup pot over medium heat and add the oil. When hot, add the meat and cook, without stirring, until the meat is starting to brown on the bottom, 3 to 4 minutes. Break it up with a wooden spoon, then add the onions and mushrooms and cook until starting to soften, about 3 minutes.
Stir in the carrots, barley and dried herbs. Add the stock or water and bring to simmer. Check the seasoning and add salt and pepper as needed. Continue to simmer until the barley is tender, 45 minutes to 1 hour. The cooking time will vary depending on the type of barley--pearled or hulled--or variety of grain you use. (If you are using cubed stew meat, you'll need to cook until the meat is tender, which may take 1 1/2 to 2 hours.)
For more ingredient substitution ideas, see the article below.