Chop an onion into large pieces and add to crock pot
Juice lemon and onion into the crock pot
Make spice blend in the following ratio 2 parts ancho chili 1part smoked paprika 1part coriander 1part oregano 1/2 part cumin
Coat the pork shoulder in the spice mix
Top with 3-4 cloves of garlic
Cook at low for 8 hours
Remove roast and for shred, add back into sauce to keep warm. Serve!