Trim pork butt of most of the fat and then cut into 1-inch cubes- they can be a bit smaller, if you like, but no larger.
In a bowl, mix together the flour, salt, pepper, and paprika; pour mixture into a shallow pan.
Dredge the pork cubes in the flour mixture (putting all the flour mixture into a Ziplock and then the meat and shaking it thoroughly can work really well, too), patting it well into the meat; try to get all of the flour mixture onto the meat.
Using a heavy skillet over high heat, heat the lard until it is smoking hot.
With tongs, carefully place the pork cubes into the hot lard piece by piece (take care that it doesn't splatter);; cook, turning frequently, until browned evenly, about 4 to 5 minutes.
Place paper towels or napkins on a plate, remove the cubed meat from the lard and put on the towels, then cover with another towel and pat so that the extra oil is absorbed.
Transfer the drained pork to a serving dish covered decoratively with lettuce leaves.
Serve with bowls of sour cream and Ninfa's Green Sauce (check the RecipeZaar database, there's at least one version posted), so that dinner guests can dip the pork cubes in either or both; make sure to have plenty of warmed, buttered tortillas nearby, too!