In a mixing bowl, whisk together flour and salt. Cut in chilled butter until it resembles coarse crumbs. Gradually add chilled water and vinegar, mixing until a dough forms. Shape into a disc, wrap in plastic, and refrigerate for 1 hour.

In a skillet, sauté onion in oil until soft. Add ground chorizo and minced pork, cooking until browned. Stir in paprika, garlic, and cayenne pepper. Remove from heat and allow to cool.

Roll out the dough to 1/8 inch thick. Use a pumpkin-shaped cookie cutter to cut out shapes. Spoon the cooled chorizo filling onto half the shapes, top with cheeses. Moisten edges, add another shape on top, and seal by crimping.

Preheat oven to 375°F. Place assembled hand pies on a lined baking sheet. Brush tops with egg wash if desired. Bake for 20-30 minutes until golden brown.