In the bottom of a large crock pot, mix salsa, green chilies and brown sugar. Add the pork and sprinkle with salt, cook on low for 6-8 hours or high for 4-6 hours. Take the meat out of the crockpot and shred with 2 forks. Return to the pot and mix with the sauce.
For the avocado cream sauce:
Slice green onions and mash the avocados. Add lime, sour cream, cilantro, garlic and salt. Mash to combine.
For the slaw:
Combine the cabbages, and onion in a large bowl. Combine the remaining ingredients in a separate bowl and then pour over the cabbage mixture and stir. Cover and refrigerate for at least 2 hours before serving. Drain before serving.
To serve, put some slaw on top of a tortilla, followed by a few spoonfuls of the pork and then a spoonful of the avocado sauce and green onions on top.
Notes
Make the slaw at least 2 hours in advance. It could go even longer, too.