In a small bowl, combine your sourdough discard, water and egg. Mix until your starter is completely dissolved and no traces of egg remain. Set aside and keep the mixture cold until ready to use.

Place flour, baking powder and salt in a large bowl, toss butter in flour mixture until all butter pieces are coated. Squish the butter pieces with your fingers.

Create a well in the center of the flour and butter mixture, pour the starter mixture in the center. Using a spatula, lightly mix your dough. Then using your hands, begin bringing the dough together with a light kneading motion.

Turn your dough out onto a large piece of plastic wrap and bring your dough together into a disc. Wrap the dough and place it into the refrigerator for 30 minutes.

Place your dough on a lightly-floured surface. Using a rolling pin flatten your dough out to roughly a 10 by 12-inch rectangle. Fold the shorter edges towards the middle like a letter.

Wrap your dough in plastic wrap and refrigerate for at least 2 hours or overnight before assembling your empanada.

Heat your oil up in a large skillet over medium high heat. Fry the potatoes in the skillet for 5 minutes, stirring so they cook evenly. Add carrots and ground beef into your skillet, stirring occasionally until the meat has browned.

Once the vegetables are tender, add in the raisins and frozen peas. Check your filling for seasoning and move your filling into a heat proof container.

Allow your filling to cool completely before assembling your empanada.

Preheat your oven to 400 F. Line two 9 by 13 baking sheets with parchment paper.

Divide the dough into 12 equal portions, about 58 grams each. Round each portion of dough into a ball, place each dough ball on a baking sheet and cover with plastic wrap. Refrigerate the dough for 15 minutes before proceeding.

Working with 1 portion at a time, use a rolling pin to flatten the dough into a 6-inch disc. Add 3 tablespoons of filling to half of your dough. Wrap dough around your filling, lining up the edges.

Place the unbaked empanada on your baking sheet and refrigerate while you shape the remaining dough portions.

Position your empanadas on your baking sheet at least 1 inch apart. Combine the egg wash ingredients. Using a pastry brush, lightly brush the empanada with egg wash.

Bake the empanadas until they are golden brown, about 15 to 20 minutes. Remove the baking sheets from the oven and carefully place your empanadas on a wire rack to cool slightly.