1 hour and up to one day before cooking, combine salt, chili powder, garlic powder, cracked pepper, coriander and mustard in a small bowl. Rub spice mixture over all sides of the pork. You want a nice, generous coating. Cover tightly in plastic wrap and refrigerate at least one hour and up to one day.
When you're ready to cook: unwrap pork (if pork has been refrigerated overnight remove from the fridge and let it stand at room temperature one hour before proceeding), and preheat oven to 500 degrees f. Place pork in a Dutch oven or heavy roasting pan. You don't add any liquid at this point. Cook 45 minutes uncovered. Meat will get dark brown and may even blacken in some places.
Take pork out of the oven and reduce temperature to 325 degrees f. Pour beer in with the pork and scatter garlic all around it. Cover the pot tightly with two layers of aluminum foil that you've poked about 10 holes in.
Return to 325 degree oven and cook an additional 2 1/2 hours. You'll know it's done when the meat breaks apart when squeezed with metal tongs and the bone slides out easily. I usually check after 2 hours to get an idea of how it's moving along. You might need a little more or a little less than 2 1/2 hours depending on your oven and the size of the butt.
While the meat is cooking make the slaw by combining cabbage, bell pepper, jalapeno and cilantro in a bowl.
In another bowl whisk together the mayonnaise, lime juice, sugar, salt and pepper. taste and adjust seasoning if needed.
Pour the dressing over the cabbage mixture and toss to coat. Cover and refrigerate for a couple of hours while the meat cooks.
When the meat is done remove it to the stove top and use the tongs to remove the center bone and start twisting the meat into bite size pieces, working it into the juices in the pan.
At this point you can choose to add a little BBQ sauce if you want to. I leave the meat as-is and put a little sauce on the bottom bun when I assemble.
Toast buns if desired, smear a little BBQ sauce on the bottom bun, top with a generous portion of pulled pork, some cole slaw and the top bun.
Get a pile of napkins ready and enjoy!