In a large bowl whisk together the flour, 1/2 teaspoon salt and baking powder. Using a pastry blender, cut in butter until flour mixture resembles coarse crumbles.
Gradually add the ice water and mix with hands until a pliable dough forms. Wrap the dough in plastic wrap and chill for at least 15 minutes.
Meanwhile, heat the avocado oil in a skillet over medium heat. Add the jalapeño and sauté for 1 minute. Add the ground beef, remaining 1 teaspoon salt and pepper. Continue to cook until the beef is no longer pink. Pour out the excess oil and accumulated juices in the skillet.
Return the skillet to medium-high heat and add the lime juice and cilantro. Continue to cook, shaking the pan, until the beef sizzles. Remove from the heat and set aside to cool.
Remove the empanada dough from the refrigerator and roll out to 1/8-inch thick on a well-floured surface.
Cut rounds using a 3-inch round cookie cutter (or cup/bowl). Dust rounds with flour and set aside. Combine scraps, roll out and cut rounds, continuing the process until no further rounds can be cut.
Preheat oven to 400F. Line a baking sheet with aluminum foil. Working with one round at a time, add 1 tablespoon of ground beef to the center. Carefully fold over edges to create a half moon shape, then crimp and seal edges with a fork. Place on the prepared baking sheet. Repeat process with remaining rounds and beef. Ensure they are spaced with 1/2-inch between each empanada on baking sheet.
Brush each empanada with melted butter then bake until golden and crisp, 8 minutes. Serve hot.