In a quest for a great challah, I found this interesting recipe at http://www.jewishfood-list.com. The original source is by Jan Weimer in The Los Angeles Times Sunday Magazine. Haven't made it yet. Although it uses schmaltz, you could use butter or oil; and instead of a big round loaf make any shape you like. Braiding challah is not difficult and you can Google many sources for instructions. Also I've never seen challah baked on a stone, so I wouldn't worry about that; you are going for a tender bread, not a crusty French-type loaf. The addition of the onions sounds fantastic. It's supposed to taste like a bread served at Morton's of Chicago.