Season beef stew chunks with salt and pepper to taste.
Place seasoned beef in a large soup pot.
Add 2 tablespoons of oil and saute for 5 minutes on high heat.
Remove meat.
Add 2 more tablespoons of oil to pot and add onions, carrots and mushrooms.
Saute for 5 minutes, stirring often.
Add garlic and thyme to pot and saute for 3 more minutes.
Add the chicken broth and 3 cups of water to pot.
Add the frozen mixed vegetables, potatoes and barley. Season with salt and pepper to taste. Stir all together and bring to a boil. Cover pot, reduce heat to low and simmer for 1 to 1 1/2 hours.