The night before you roast the pork, coat it heavily with the dry rub. Wrap in plastic wrap or place in a plastic bag, and refrigerate overnight
Remove the pork from the refrigerator 30 minutes prior to cooking. Place in the slow cooker and gently pour in the chicken stock around it. Try not to splash the dry rub with the stock. You'll end up with more juice as the pork is being slow cooked
If roasting with oven:
Preheat the oven to 250 F. Put the pork butt, fat side up, in a roasting pan with enough apple juice to cover the bottom of the pan. Cook in the oven until the exterior of the pork is mahogany colored, about 4 hours, adding more apple juice as needed. If the exterior is drying out, spray the pork with apple juice. Carefully transfer the pork to long pieces of the double-layered heavy-duty foil. Pull up the sides of the foil, add 1/2 cup apple juice to the foil, and wrap so it's as airtight as possible. Return to the oven and cook until the internal temperature of the pork is 190 F to 195 F, 4 to 5 hours
Preparing the sauce and green onion slaw:
Combine the vinegar, mustard, honey, salt, and pepper in a blender and blend until smooth. With the motor running, slowly add the oil until emulsified
Place the green onions, vinegar, chiles, mayonnaise, salt, pepper and oil into a blender and blend until emulsified. Place the cabbage and red onions in a bowl, add the dressing and stir until combined. Fold in the cilantro and season with salt and pepper, to taste
Assembling:
Let the pork cool down and shred the pork to the desired consistency. Place the bun on the pan and let them toast slightly, you don't need to if you don't want, but I like to do this so my bun is not soggy! Drizzle the sauce on the top and bottom of the bun. Top the bottom bun with the meat, another generous drizzle of sauce, green Onion Slaw and finish with the top of the bun. Enjoy !!!