Argentinian chimichurri, the much-loved herbal, garlicky, vinegary sauce often paired with grilled meats, gave us the idea for the vinaigrette that dresses this hearty but easy-to-make salad. We cook the diced sweet potatoes in the microwave—no need to dirty pots or pans, and they’re done in about five minutes. It’s important to dress the potatoes while they’re still warm so they absorb the flavorings. We especially like the pepperiness and tender texture of arugula in this salad, but baby spinach works nicely, too.