For a low-carb meal that combines a sophisticated Niçoise salad and an All-American tuna-salad sandwich, look no further than these lettuce cups. The romaine lettuce leaves cradle chunks of white tuna, chopped hard-boiled eggs, salty Parmesan, and a splash of store-bought Caesar salad dressing. And low-carb’s just the beginning. This recipe also packs in the omega-3s and protein. Look for canned tuna that’s troll- or pole-caught, both environmentally sustainable fishing practices that ensure other sea creatures aren’t snagged in vast tuna nets. Turns out, it’s worth spending a bit more on great canned tuna; tasty and eco-conscious brands include Wild Planet, American Tuna, and Ocean Naturals.