1. In a food processor, combine half the avocado, the buttermilk, sour cream, lime juice, salt, onion powder and garlic powder. Purée until smooth. Add cilantro; pulse just to combine. Chill.
2. Cut the remaining half avocado into 16 thin slices. Lay one slice of prosciutto on a work surface. On the prosciutto, place one slice each avocado, jalapeño and cheese.
3. Tuck in the sides of the prosciutto and roll tightly. Coat the roll in cornmeal, dip in egg, then again in cornmeal. Repeat with the remaining prosciutto, avocado, jalapeño and cheese.
4. In a 4-quart saucepan over medium-high heat, heat two inches of vegetable oil to 365° F. Working in batches, fry the poppers until golden brown, about 2 minutes. Remove with a slotted spoon and drain on paper towels. Serve with the Avocado Cilantro Lime Sauce.