Shit, now I'm thinking about it and you'd need something big like a flank steak or a brisket. I don't think a pork-loin would work since it's not broad enough. You'd still need to probably butterfly it, and then fringe the edge so you had strands to work into the braid. Best I can think of would be more like braided filled pastry than anything else. Not a terrible sway to do a stuffed roast or roulade I guess.