- 1 3/4-ounce package dried porcini mushrooms (about 3/4 cup)
- 1 1/2 cups raw whole grain buckwheat groats (about 11 ounces)
- 1 large egg, lightly beaten to blend
- 2 tablespoons vegetable oil, divided
- 3 large onions, chopped (about 5 cups)
- 8 ounces assorted fresh mushrooms (such as crimini, button, oyster, and stemmed shiitake), coarsely chopped
- 1 1/2 cups (or more) vegetable broth
Place porcini in small bowl with 1 1/2 cups boiling water. Let soak until mushrooms are soft, 1 hour. Remove mushrooms from liquid; squeeze dry. Set mushrooms aside. Strain soaking liquid, leaving any sediment behind. Reserve soaking liquid.
Combine buckwheat groats and beaten egg in heavy large pot (preferably nonstick). Stir over medium heat until grains are separated and lightly browned, 10 minutes.
Heat 1 tablespoon oil in large nonstick skillet over medium-high heat. Add onions and sauté until golden brown, about 15 minutes. Transfer onions to bowl. Add remaining 1 tablespoon oil, all mushrooms, and garlic to same skillet. Sauté until mushrooms are brown and tender, about 7 minutes. Add 1/2 cup reserved porcini soaking liquid and boil until liquid evaporates. Remove from heat.
Add remaining reserved soaking liquid and 1 1/2 cups vegetable broth to pot with buckwheat groats. Cover and cook over medium-high heat until buckwheat groats are almost tender, stirring occasionally and adding more vegetable broth by 1/4 cupfuls if needed, about 20 minutes. Add onions and mushrooms to pot and cook until heated through. Season with salt and pepper.