In a food processor, pulse the gluten free all-purpose flour, salt, and cubed cold butter until coarse crumbs form. Add the egg and ice water, pulsing until a dough ball forms. Wrap and chill for 30 minutes.
In a skillet, cook the ground beef and diced onion over medium heat until browned. Drain grease, add the cumin and salt, and let cool completely before mixing in the shredded cheddar cheese.
Preheat the oven to 400 degrees fahrenheit and line a baking sheet with parchment paper.
Roll out the chilled dough between parchment paper to 1/8 inch thick. Use a 4-inch round cutter to cut out dough circles.
Place a spoonful of the beef filling in the center of each circle. Fold the dough over to create a half-moon shape and crimp the edges tightly with a fork.
Place on the baking sheet, lightly brush with an egg wash if desired, and bake for 18 to 20 minutes until golden brown.