Deli roast beef makes this salad super fast and easy; ask for it to be sliced a little thicker, which allows it to hold up well in the salad. Leftover steak, chicken, salmon, or shrimp work equally well. The dressing can be made ahead of time and doubled or tripled to make future salad prep even faster. Fish sauce is a salty Asian condiment available in larger grocery stores, gourmet stores, and international markets.