Make the dough: Combine flour, butter, and salt in a large bowl, and using your fingers, rub butter into four until pea-size crumbles form. Add 1 1⁄2 cups warm water and stir until dough forms. Knead in the bowl until smooth, about 4 minutes. Wrap in plastic wrap, and refrigerate for 1 hour.
Meanwhile, heat 1⁄4 cup olive oil in a 6-qt. saucepan over medium-high heat. Season beef with salt and pepper, and add to pan; cook, turning once, until browned on both sides, about 8 minutes. Add garlic, carrots, quartered onion, and 6 cups water; bring to a boil. Reduce heat to medium-low, cover, and cook until beef is very tender, about 2 1⁄2 hours.
Remove from heat, and let beef sit in saucepan until cool enough to handle, about 30 minutes. Transfer beef to a cutting board, and reserve 1 cup cooking liquid; discard remaining liquid and vegetables or reserve for another use. Shred meat into thin strands, and then finely chop; set aside.
Wipe the saucepan dry, then heat remaining olive oil over medium-high heat; add minced onion, and cook, stirring, until golden brown, about 12 minutes. Add chile powder, oregano, and cumin, and cook for 1 minute. Add reserved beef and cooking liquid along with raisins, olives, sherry, sugar, and pine nuts; bring to a boil. Reduce heat to medium, and cook, stirring occasionally, until raisins are plump and meat has absorbed most of the liquid, about 20 minutes; set aside to cool.
Divide dough into 24 balls, and place on a work surface; using a small rolling pin or the heel of your hand, flatten each ball into a 5" disk, brush edges with water, and place 2 tbsp. filling in the center. Fold disks in half to form half-moons, and seal edges together using the tines of a fork. Refrigerate empanadas for at least 1 hour, or up to overnight.
Pour oil to a depth of 2" in a 6-qt. saucepan, and heat over medium-high heat until a deep-fry thermometer reads 350°. Working in batches, fry empanadas until browned and crisp, about 6 minutes. Transfer to paper towels to drain before serving.