Preheat the oven to 350 degrees. Bring a large pot half filled with water to a boil. Cut out the hard center cabbage core. Remove the large cabbage leaves. Place the cabbage leaves plus the smaller remaining cabbage in the boiling water. Cook the cabbage leaves for about 3 minutes, or until they wilt. Cook the remaining cabbage core for 3-5 more minutes, or until you can easily remove the leaves. Cut off the hard stem portions from the large leaves so that they can be rolled easily. Set the leaves aside. ALTERNATELY: if you plan ahead you can freeze the entire head of cabbage for 24 hours (or more). Thaw the cabbage and the leaves will already be wilted and you can avoid cooking them.
In a large bowl, mix the ground beef, onion, egg, rice, matzo meal and salt and pepper to taste. Place a mound of this mixture in the center of each leaf (more on the larger leaves of course). Enclose the meat by wrapping the cabbage leaves, envelope style. Place the stuffed cabbage leaves, seam side down, in deep baking dishes. (I separate the large rolls and smaller ones.)
Heat the vegetable oil in a saute pan over medium heat. Add the onion and cook for 4-5 minutes or until softened. Stir in the brown sugar, chili sauce, lemon juice and raisins and cook for 3-4 minutes. Pour the sauce over the cabbage rolls. Cover the pan. Bake for 2 hours (or, to cook ahead, bake for one hour, freeze, thaw and bake for an additional hour).