Combine the rice and water in a medium saucepan. Bring to a boil, stir gently, cover and cook for about 20 minutes. Cool in a large bowl. Core the cabbage and place it in a large pot or Dutch oven half filled with water, cover, and bring to a boil. Cook about 2 minutes. As the outer leaves become translucent and soft, pry off and remove with a wooden spoon. Continue until the head is about 5 inches in diameter, remove and save for Cabbage Filling, (Recipe will be included in the next bunch). Trim the leaves by paring of the thick part of the rib. In a large skillet, saute the chopped onions in melted butter until lightly cooked. Add the onions and mushroom mix to the rice, stir gently but do NOT mash. Add salt and pepper to taste. Line the bottom of a baking dish with the outer cabage leaves. Place a large spoonful of the filling at the stem end of each leaf, fold over the sides and roll from the bottom to the top. Do NOT overstuff or the results will look like hand granades. The rice will expand when baked. Without crowding, arrange in neat layers in the baking dish, covering the last layer with a few cabbage leaves. Coarsely chop the tomatoes and pour over the rolls. Add the bouillon cube or Maggi seasoning, cover, and bake in a preheated 325 Degree F. oven for about 2 hours. Add tomato juice or water as needed, there should be 2 to 3 inches of liquid at the bottom. Baked rolls will keep hot for about 1 hour.
Yield: About 2 dozen.
To freeze before baking, place the rolls on an oiled baking sheet and freeze until rigid, then store in heavy plastic bags.
Serve with mushroom gravy.