In a large bowl, stir together the flour and salt. Add in the butter and cut in with your fingers or a pasty blender until it resembles coarse crumbs the size of peas. Make a well in the center and add in the ice water and beaten egg. Use a wooden spoon or spatula or mix the dough until it comes together. Form into a disk and cover with plastic wrap. Chill in the fridge for at least 30 minutes or overnight.
Set a large skillet over medium high heat. Once hot, drizzle in the oil and add the corn kernels, onion and jalapeño. Cook, stirring often, until the veggies soften and begin to brown, about 8 to 10 minutes. Season with granulated garlic, oregano, cayenne, and a large pinch of salt and pepper. Transfer the mixture to a mixing bowl and set aside to cool slightly.
Add the crema, cotija, lime zest, lime juice and cilantro to the cooled corn mixture. Stir until evenly combined. Set aside.
Preheat oven to 375°F. Line a baking sheet or two with parchment paper.
Remove the chilled dough from the fridge and transfer to a lightly floured work surface. Cut into 8 or 12 even portions. This depends on the size you want for your empanadas. I chose a heartier eight. Working with one piece at a time, roll out into a circle, about 1/4 inch thick. Add a few spoonfuls of the filling on the center and brush the edges with egg wash. Fold over and crimp the edges to seal the empanadas. Place on the prepared baking sheet and continue filling and shaping the rest. Space them out on the baking sheet so they have space to bake properly.
Brush the empanadas with egg wash and bake until golden brown, 35 to 40 minutes.
Meanwhile, to make the sauce, in a small bowl, whisk together the crema, cilantro, lime zest, lime juice, cotija, and a pinch of salt and pepper. Cover and chill until ready to use.
Remove the empanadas from the oven and allow to cool slightly. Serve warm with the crema for dipping. Enjoy!