Wash the rice in water once or twice, then drain and set aside. Melt 2 ounces of the butter in a skillet and saute the rice for 3 to 5 minutes. In a saucepan you can cover tightly, bring the stock to a boil. Add saffron, paprika, and cumin, as well as a dash or two of mushroom soy sauce, if the stock is not salted. Add the rice, return it to a boil, and simmer, covered, over low heat for about 20 minutes, until all liquid is absorbed. Saute the mushrooms in 2 to 3 ounces of butter and a bit of olive oil, seasoning them with a dash or two garlic powder, black pepper, red wine, Madeira, and a few dashes of mushroom soy sauce. Add the walnut meats and saute for an additional 4 minutes. Set this aside. When the rice is done, stir in 2 to 3 tablespoons of sour cream enough to make it sticky. Gently stir three-quarters of the mushroom mixture into the rice. Put the rice into 4 small au gratin dishes (or one big one) and put the rest of the mushrooms on top. Bake at 400 degrees F for 8 to 10 minutes, and you have the right rice.