I'm interested in making a traditional Christmas pudding but I've never seen suet available in the stores around here. Assuming I can't find any, what would be a good substitution?
For Christmas pudding, there really is no substitute. In some recipes it's possible to use finely grated, very hard, unsalted butter, or a vegetable shortening, but the results are just not the same.
Use beef fat or lard if your butcher can't supply.