Use a food processor or stand mixer to mix the flour and salt. Add the butter, cut in small chunks, and pulse until mixed.
Add the egg and the water (in small increments) and continue pulsing until a clumpy dough forms. To make the empanada dough by hand, follow the same process, but use your hands to mix the ingredients together.
Split the dough into 2 large balls; flatten slightly into the shape of disks. The dough can be used immediately or refrigerated until ready to use (1-2 days max).
To make the empanada disks, roll out the dough into a thin sheet and cut out round disc shapes for empanadas (use round molds or a small plate). OR
You can also make small individual balls with the dough and roll out each individual ball to a round shape (doesn’t need to be perfectly round) – if you have a tortilla press you can use it to flatten the dough balls.
Mix the grated mozzarella, chopped tomatoes, and basil in a bowl.
To assemble the empanadas, place a spoonful or two of the cheese mixture on the middle of each empanada disc.
Fold the empanada discs and seal the edges. You can either use a fork to help seal the empanadas, or use your fingers to twist and curl the edges creating a churito or curl type seal. You can also use an empanada mold to seal the empanadas.
If you have time, for best results, especially since these empanadas contain cheese, chill the empanadas for at least 30 minutes before baking, this will help them seal better and prevent leaks.
Before baking, brush the top of the empanadas with the shisked egg mix; this will give a nice golden glow when they bake.
Bake in a pre-heated oven at 400F (200 C) for 18-20 minutes or until golden on top.
Serve the caprese empanadas with your choice of dipping sauce.
Notes
These caprese empanadas can also be fried - they will be less likely to leak out the cheese filling if they are fried.To fry them you can use a deep fryer or a basic frying pan, make sure to have enough oil to cover at least half the empanada if using a pan.Heat the oil and fry the empanadas until they are golden on both sides. Don´t overcrowd the pan, depending on the side cook 3-4 at a time. Place the fried empanadas on paper towels to remove any excess oil.