Start by mixing 1.5 teaspoons of salt into 3 1/4 cups of flour. Dice up 6 oz. of butter (1.5 sticks) into small 1/2" chunks and plop them into the flour. Use your fingers to disintegrate some of the butter into the mixture but don't worry about getting all of the butter dissolved. Mix it in just enough to make the mixture crumbly with a few chunks of butter laying about.
In a bowl, combine 2 small eggs, 1.5 tablespoons vinegar, and 1/2 cup ice cold water. Add this mixture to the flour and use a fork or spatula to roughly combine.
Dump onto a work surface but resist the temptation to knead! Just combine it enough to form a cohesive ball. Cover with plastic wrap and chill in the refrigerator for at least two hours.
For the beef mixture, saute 1/2 onion in a dollop of oil over medium-high heat for a few minutes. Add ground beef and cook until browned. Drain any fat if you want. Add 2 cloves minced garlic and saute briefly. Add 2-3 minced chipotles, 1 Tablespoon adobo sauce, 1-2 Tablespoons chili powder (I used New Mexican), 1/2 teaspoon cumin, 1/2 teaspoon salt, and freshly cracked pepper. Add a splash of water and let simmer over medium heat, stirring well.
Once the dough has been chilled you can roll it out. If using a cutting board roll out 1/4 of the dough at a time. Sprinkle your work surface and rolling pin with flour before starting. Roll the dough down to 1/4" thickness or less.
Use a biscuit cutter or bowl to cut out circles of empanada dough. Fill each round with 1-2 Tablespoons of beef mixture and plenty of cheese chunks. Lift both edges of the round and seal the edges using your fingers. Use a fork to seal the edges further.
For the eggwash, crack an egg in a bowl, add a splash of water and whisk. Brush the empanadas with the eggwash.
Bake at 400F for 20-25 minutes or until golden brown. Let cool for a few minutes before serving.