Heat oil in large skillet over medium-high heat until hot. Add pork, garlic and hoisin sauce; cook and stir 4 to 5 minutes or until pork is no longer pink. Add bok choy, carrots and onions; cook and stir 1 minute or until vegetables are crisp-tender.
Spoon about 1/2 cup pork mixture onto half of each warm tortilla. Fold each in half. Serve tacos with tempura sauce.