The night before: Mix together brown sugar, cayenne pepper, cumin, and salt. Then rub this mixture on roast. Put in crock pot on low. Cook all night. (My crock pot runs HOT, so I only cook mine for four hours instead of 8. But, others that have tried this recipe swear by the overnight rule.).
The next morning: Add Coke, chicken stock, garlic, onion. Continue cooking on low all day. (Again, I only do this for four more hours. I use a meat thermometers to make sure it's done.).
An hour before serving: Add the last cup of brown sugar.
Mix the salad dressing in a blender. Add lime juice to taste. Chill for several hours. If you like your dressing a little thinner, add buttermilk.
Shred the lettuce, pull the pork and put it on top of the lettuce, add beans, salad dressing, and broken tortilla chips. Enjoy!