Korean Pulled Pork Tostadas

1. Mince scallions, garlic, and ginger in a food processor. 2. Whisk together soy sauce, chili paste, vinegar, brown sugar, and minced scallion mixture; reserve half. 3. Trim excess fat from roast and discard. 4. Cut roast into 4 to 5 equal pieces; place in slow cooker. 5. Pour the water + half the soy sauce mixture over pork. 6. Cover slow cooker and cook pork until fork-tender on high heat, 3-4 hours. 7. Remove pork from slow cooker and using two forks, shred; tent with foil. 8. Transfer reserved liquid to a saucepan, bring to a boil over medium-high heat and reduce to 1 cup, about 10 minutes. 9. Add reserved soy sauce liquid to saucepan and heat through, then toss with pork. 10. Serve pork on tostadas with your choice of pickled sides.