Drain cooked beans and mix in the yogurt.
Slice mushrooms thin and cook with the onion, garlic and ginger for five minutes.
Stir in the flour and keep stirring and cook for five more minutes. Add the vegetable broth, sherry and soy sauce, reduce heat to low and cook, stirring until sauce is thick and smooth. Cut the broccoli so that the stems are sliced very thin and the flowerettes remain in bite-sized bunches. Combine soybeans, broccoli and sauce in casserole dish. Add salt, pepper and flax.