1 1/2 cups (250 grams) pearled or quick-cooking barley
2 tablespoons olive oil
2 large cloves garlic, chopped finely
5 medium sage leaves, finely chopped (about 1 tablespoon)
3 1/2 ounces (about a dozen medium-sized) fresh shiitake mushrooms, stems removed and caps sliced 1/8-inch thick
1 tablespoon soy sauce
1 1/2 teaspoons freshly squeezed lemon juice
In a medium (3-quart) saucepan, bring two quarts of water to a rolling boil. Add the barley and cook until cooked through and chewy, 15 to 30 minutes depending on the variety. When done, drain the barley into a colander in the sink and set aside.
While the barley is cooking, heat the olive oil and garlic in a medium or large (10- or 12-inch) stainless steel or cast-iron skillet over medium heat. When bubbles begin form around the edges of the garlic (after about 1 minute), add the sage and mushrooms. Sauté until the mushrooms have begun to brown around the edges and golden-brown bits have begun to stick to the bottom of the pan, about 5 minutes.
Turn off the heat under the skillet, then add the soy sauce and lemon juice. Use a wooden spoon to scrape up all of the browned bits from the bottom of the pan, stirring them into the mushrooms and sage.
Add the barley to the skillet and stir until the grains are coated and the mushrooms are distributed evenly throughout. Serve warm.