2 tablespoons vegetable oil
2 green onions, halved and thinly sliced
1 red onion, chopped
1 cup water
2 tablespoons vinegar
3 cloves garlic, minced
1 (15 ounce) can stewed tomatoes, chopped (optional)
1 (15 ounce) can mushrooms, chopped (optional)
1 (15 ounce) can chicken broth
1 (15 ounce) can black beans, rinsed and drained
1 cup chicken broth
2 carrots, sliced
1 (28 ounce) can sliced mushrooms
Combine vegetable oil, onions, and red onion in a large saucepan. Bring to a boil. Reduce heat to low.
Meanwhile, in a large bowl, combine the water, vinegar, garlic and stewed tomatoes. Stir together; whisk into the boiling mixture. Cover bowl, reduce heat to low, and simmer until thickened, about 10 minutes.
While the bouillon is warming, remove the green onions and cut into wedges. Place mustard-sized pieces into the mushrooms and vegetables.
Return bouillon to the pot and heat over medium high heat until very thick. When the sauce thickens, reduce heat to low and stir in the chicken broth and black beans. Continue to heat over medium heat until the soup begins to simmer, about 5 minutes. Reduce heat to low and whisk in the soup until well blended. Serve immediately.