1 3/4 cups homemade or low-sodium store-bought chicken stock
3/4 ounce dried porcini mushrooms
1 tablespoon olive oil
1 small onion, thinly sliced
2 cloves garlic, thinly sliced
1/2 teaspoon coarse salt
1/4 teaspoon freshly ground pepper
4 ounces fresh white mushrooms, quartered
3 small tomatoes (about 1 pound), coarsely chopped
1 small sprig fresh rosemary, plus more for garnish
1 can (19 ounces) white beans, drained and rinsed
Bring stock and 1/2 cup water to a boil in a small pan. Add porcini. Let stand until soft, about 20 minutes. Remove porcini with a slotted spoon; coarsely chop. Set aside. Strain soaking liquid through cheesecloth; set aside.
Heat oil in a medium pan over medium-high heat. Add onion, garlic, salt, and pepper. Cook, stirring occasionally, until onion is translucent, about 3 minutes. Add white mushrooms; cook, stirring occasionally, until tender, about 5 minutes. Stir in porcini, tomatoes, rosemary, soaking liquid, and beans. Bring to a boil. Reduce heat to medium; simmer until cooked through, about 15 minutes. Remove cooked rosemary; discard. Garnish with fresh rosemary sprigs.