1Whisk together the 2 cups flour, salt, and sugar in a bowl until evenly blended; make a well in the center of the mixture. Whisk the egg yolk and water together in a small bowl until smooth; pour into the well and mix to form a stiff dough. Transfer the dough to a lightly floured surface and knead until smooth and elastic, about 8 minutes.
2Roll the dough with a rolling pin until thin, sprinkling with flour to prevent from sticking. Brush with melted butter and roll it like a jelly roll. Cut with a sharp knife into 1 1/2-inch slices. Roll each piece into a circle and fill with about 1 tablespoon filling. Fold over into half moons and seal.
If baking the filled empanadas, brush the top of each with beaten egg white just before baking at 350 degrees F (175 degrees C) until golden brown, about 30 minutes.
Tip
Aluminum foil helps keep food moist, ensures it cooks evenly, keeps leftovers fresh, and makes clean-up easy.