The idea for this recipe came from Peruvian ceviche, which often is served with a side of boiled sweet potato. We skip the fish and let the potato take center stage, seasoning it like ceviche with lime, red onion, chilies and cilantro, plus coconut milk for richness. No stovetop cooking is needed; to streamline prep, the sweet potatoes are steamed in the microwave. Be sure to toss them with the dressing while warm so they absorb all the flavors. If you like, garnish with crushed corn nuts, a nod to the toasted, salted Andean corn kernels known as canchitas that often are sprinkled over ceviche.