There are many recipes for Rinderroulden (beef roll-ups), but I enjoy Susanne’s the best. She uses thinly sliced prosciutto that she buys at Trader Joe’s (instead of bacon) as well as cornichons (gherkin pickles). The butcher slices a piece of London broil into 1/8 inch thin slices. I find that this dish develops more flavor when made a day ahead.