In a medium pot, cover potatoes with cold water, and bring to a boil over medium-high heat.   Simmer, covered until tender, about 15 minutes. Drain well, and transfer to a large bowl. Add ricotta, milk, butter, and olive oil. Mash with a potato masher until only a few chunks remain, and mixture is creamy. Stir in cheese, salt, cumin, chili powder, onion powder, and hot sauce; set aside.

Lay out egg roll wrappers on a large work surface. Place ¼ cup filling in the center of each wrapper. Working with one wrapper at a time, brush the edges lightly with water. Position the wrapper so that one point (corner) is closest to you. Fold that corner up just enough to cover the filling. Fold each side over to meet in the middle and roll up from the bottom. Brush final corner with water, and press lightly to seal.

Line a sheet pan with two layers of paper towels.  Heat ¼-inch oil in a large skillet over medium to medium-low heat. Working in batches, fry egg rolls until golden brown and crispy on all sides, using tongs to turn them so they brown evenly, about 3 to 4 minutes. Drain on the prepared pan. In a small bowl, combine sour cream, lime zest, lime juice, cilantro, and more hot sauce if desired. To serve, smear a heaping tablespoon of sauce on an appetizer plate. Cut egg roll in half and place both halves in the center. Can also be served on a large platter with the dipping sauce in a small bowl.