In a large stockpot, heat the olive oil over medium-high heat. Add the onion and sauté until translucent and soft, about 6 minutes. Add the mushrooms and stir to coat with oil. Sauté for 5 minutes, or until the mushrooms have released their liquid and are starting to brown.
Add the barley and stir to combine. Stir in the wine, if using, and cook until the liquid is absorbed. Stir in the carrots. Pour in the broth and raise the heat to high. Add the bouillon and stir until it is dissolved. Cover the pot and bring the broth to a rolling boil. Turn the heat down to a simmer and cook, covered, for 45 minutes, or until the barley is tender.
When the barley is tender, stir in the kale. It will look like a lot, but as you stir it in, it will wilt down. Taste and add salt if needed.