Combine flour, masa and salt
Combine egg, water and vinegar
Cut the butter into cubes and cut into the flour mixture.
When there are no large chunks of butter remaining, mix in the egg mixture.
Knead the dough a couple of times just until smooth. Wrap and refrigerate for at least one hour.
On a floured surface roll the dough into 1/8 inch thickness. Using a 4 1/2 inch diameter cutter, cut as many rounds from the dough as possible. Gather the scraps for back into a ball, cover and refrigerate for 30 minutes.
Combine 1 1/2 cups of pork with the chilled collard greens.
Reroll the rest of the dough and cut rounds. Discard any scraps. There should be 15 rounds.
Fill each round with 1 1/2-2 tbsp of pork filling. Brush one side with water and fold in half. Press the two sides together and crimp with a fork. Repeat until all empanadas have been made. Chill until ready for frying.
Heat a pot of oil until it reaches 350 degrees. Fry empanadas until golden brown. Drain on a paper towel and season with salt.
Serve with green tomato salsa and crema.