Beef Picadillo Empanadas

Name: Beef Picadillo Empanadas
Ingredients: 2 1/4 cups all-purpose flour; 1 1/2 teaspoons kosher salt; 4 ounces (1 stick) cold unsalted butter, cut into 1/2-inch cubes; 1 tablespoon distilled white vinegar; 2 tablespoons olive oil; 1 small white onion, diced; 1 egg; 1/3 cup ice water; 2 garlic cloves, minced; 1 pound ground beef; 1 tablespoon tomato paste; 2 to 4 tablespoons pureed canned chipotle; 1 teaspoon adobo seasoning; Kosher salt; Freshly ground black pepper; Vegetable oil, for deep-frying (optional); All-purpose flour, for assembly; 1 to 2 large egg whites, beaten, for assembly