Place the onion, carrots, celery, mushrooms, barley, vegetable broth, smoked paprika, thyme, bay leaves, garlic, and soy sauce in the slow cooker.
Stir everything together until the spices are evenly distributed.
Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours, until the barley is tender.
Remove the bay leaves and season with salt and black pepper before serving.
Notes
Check the soup near the end of cooking and add a splash more broth if the barley has absorbed too much liquid. Leftovers keep well in the fridge for three days and reheat smoothly on the stovetop with a little extra broth to loosen the texture.Course: Soup
Cuisine: American
Equipment: Slow Cooker