Easy and utterly delish Barbecoa or "Mexican Shredded Beef" Crockpot

I know real Barbecoa is a whole head simmered till tender and shredded out of it and put into tacos etc.  I am so not doing all that. But instead I have found a ridiculously easy recipe using the crockpot.  There are of course endless variations but here is mine with a bit more of a bent to healthy.

3 pound bone in chuck roast.  (I have seen sirloin, flank etc.  Chuck is best for this)
1 cup of beef stock
1 chopped onion
5 cloves of garlic smashed
1 tbsp of chipotle powder OR chili powder
1 tbsp of cumin
1 tbsp of oregano
salt/pepper to taste
1/4 cup of apple cider vinegar OR red or white vinegar will work fine.
A few sprigs of cilantro, optional.

For freezing sauce:
Chipotle in adobo sauce
2 tbsp or so of chopped cilantro (optional)
salt and pepper to taste
1/2 cup of mojo (bottled or homemade)
Cumin
Oregano
3 peeled cloves of garlic
1 small chopped onion
1 small tomato, chopped
1/2 cup of water

Rub the meat with the spices on both sides, add to crockpot with rest of the ingredients and set cooker to low.  Let it cook for 10 hours.  Now here is the hard part, you HAVE to do the next steps exactly as written here to get best results.  I have tasted it with and without and let me tell you it's a huge difference in taste/yumminess.

When ready, turn off heat and let it cool as you make the freezer sauce.  In a sauce pan, put enough oil to cover bottom, saute onions till soft.  Add garlic and cook till fragrant.  Then add rest of ingredients.  I put in one pepper and a spoonful of the adobo sauce.  You can add more to taste.  Let it simmer on medium till slightly reduced.  About 5 minutes.  Let cool.  Then with a stick blender or put in a blender, puree till smooth.  Set aside.

Remove meat, discard juice.  Shred meat into a large baggie.  Leave off bones, fatty tissues etc.  Pour the freezer sauce you just made and massage it through.  Seal well and place in freezer. YES, you must do this step.  Let it completely harden, about 6 hours to overnight.  Then let it thaw in refrigerater all day.  You can then put into a sauce pan and bring it up to temperature.  I also used a microwave as well. 

I served it on lightly charred corn tortillas with avocado, red onions and a squeeze of lime.  You can eat it straight out of the pan.  However you want, but it's so good.