The hardest part of making a great veggie reuben sandwich is finding a substitute for the cure-ed-ness of corned beef. I’ve found grilled portobello mushrooms, eggplant, and artichoke hearts acceptable, but lacking that deli taste. On my way to a solution, I have ground a bottle of pickling spices to a coarse powder and sprinkled this in the sandwich. Not perfect, but much better.