Preheat oven to 375 degrees.
Place peppers in an oiled baking dish and bake for 15 minutes.
Let peppers cool and pour out any water that accumulated in the bottom of the pepper.
Meanwhile, bring a small pot of water to a boil. Add salt to taste and add barley. Cook until al dente (tender but with some bite).
Drain, rinse with cold water, drain again and set aside.
Heat 2 tablespoons oil in a skillet or saute pan.
Add the onion and cook 7-8 minutes or until softened.
Add garlic, chili powder, cumin, coriander, oregano and cayenne pepper. Stir, then add tomato sauce and beef broth.
Bring to a boil, reduce heat and simmer 5 minutes or until thickened slightly. Season to taste with salt and black pepper.
Transfer 1 cup of the sauce to a large bowl and let cool. Add the barley, beef, egg, 1 cup cheese and mix well.
Fill peppers with equal amounts of the filling. Pour remaining sauce over the peppers, cover with foil and bake 40-45 minutes or until cooked through to 165 degrees in the center.
Top with cheese, return to the oven and bake another 10 minutes or until cheese has melted.