cabbage strudel question without butter

Same as butter.....spreads just like melted butter.

I have never tried a substitute for the butter. I was trained in a French kitchen, and the only thing we used with puff pastry was butter. However, I know my vegan and dairy intolerant friends will substitute coconut oil, margarine (yuk) lard...obviously not vegan. Hope this helps, let me know what you end up with. The bottom line, is to create the layers within the puff pastry you have to have pastry/fat pastry/ fat etc. Its the layers that make the pastry. Grandma Katz would have made Hungarian Strudel which is just a form of puff pastry...but would have used butter.