2. Heat the olive oil in a large skillet over high heat. While the oil heats, season the chicken with salt and pepper. Add the chicken to the pan and brown on all sides.
3. Add the wine, letting it boil rapidly for a minute and then stir with a wooden spoon to remove any browned bits that may be stuck to the pan.
4. Add the mushrooms, reserved liquid and the tomatoes. Turn down the heat so that the mixture simmers slowly and place a lid, slightly ajar, over the skillet. Cook until the chicken is completely tender, about 25 minutes. Taste the cooking liquid and adjust the salt and pepper to taste.
5. Meanwhile, heat the oil over medium-low heat in a small oven-proof pot. Add the onion and cook until it becomes translucent but not brown, about 3 to 4 minutes.
6. Add the barley, a pinch of salt and a few twists of freshly ground pepper. Stir to coat the barley evenly with oil. Cook for 3 to 4 minutes.
7. Add the broth and bring to a boil over high heat. Lower the heat so that the broth is barely simmering, cover with foil and cook until the barley is tender, about 20 minutes.
8. Divide the barley among 4 bowls, spoon the chicken mixture over the top and serve.