The thing that makes this steak salad so great is that it’s equally as delicious served warm for dinner as it is prepped overnight and eaten cold for lunch the next day. The potatoes only get better as they hang out in the harissa vinaigrette, which does double duty as a dressing for the salad. (Harissa pastes vary greatly in their relative spiciness and funkiness, so try a few different brands to figure out which you like best. And remember: when incorporating into dressings, stir it in little by little until it tastes right.) If saving for lunch, the key to unwilted greens is all in the proper layering technique: Pack them on top of the cooled steak and potatoes, and wait until the very last moment to toss or shake it all together.