Combine flour and salt in food processor and blend to combine.
Add butter cubes and pulse until mixture resembles corn meal – it’s OK if there are a few small lumps of butter.
Combine egg and water in a small bowl and whisk together.
Add to flour mixture and pulse just until combined. If dough seems very dry, add a tablespoon more of ice water.
Turn out onto lightly floured surface and form dough into a flat rectangle, wrap in plastic wrap and chill for at least one hour.
Preheat oven to 400 degrees.
Divide dough in 12 equal balls and roll out each into a circle about 5 inches around and 1/8 inch thick. Place about 1 1/2 tablespoons of filling in center.
Lightly dampen one edge of the round. Fold dough in half and press edges to seal, then pinch and crimp edges decoratively. Place on a baking sheet.
Brush each empanada with beaten egg and water.
Bake about 25 minutes, until golden.
Cool on a rack for 10 minutes.
To serve, accompany each empanada with a spoonful or small ramekin of Cilantro Mojo Sauce.