Wash sweet potatoes and place in a deep saucepan with cold water to cover. Bring to a boil and cook until tender. Remove from heat, drain and allow to cool enough to handle. Peel off the skin, slice into 1/2 inch pieces, and set aside.
Place the bay scallops in a medium bowl and toss gently with the lime juice. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes or up to 1 hour.
Place the coconut on a rimmed baking sheet and toast until golden brown, about 5 minutes, stirring every few minutes so the coconut toasts evenly. Set aside.
Drain the scallops and transfer to a clean bowl. Add the onions, jalapenos, raisins, toasted coconut, coconut milk, chopped cilantro, oregano, and salt and pepper, to taste. Mix well and refrigerate for at least 30 minutes and up to 3 hours. Sprinkle with cilantro leaves and the reserved toasted coconut and serve with Canchita on the side.
Canchita, the Un-popped Popcorn of Peru:
Heat the canola or vegetable oil in a large pot over medium-high heat for 2 minutes. Add the chulpe corn, cover the pot and reduce the heat to medium. Once you hear the kernels pop (like popcorn), shake the pot vigorously to prevent the kernels on the bottom from burning. Once the popping slows, after about 8 to 10 minutes, drain the canchita in a strainer and rub with a paper towel to remove excess oil. Season with salt while the corn is still warm and serve with Scallop Ceviche.