Marinate the chunks of Pork and add the solids and part of the marinade liquid in with the lard.
The following marinade is authentic, but there are many authentic variations, e.g. some use milk.
Traditional Carnitas de Cerdo
Dry brine 2"-3" cubes of pork, then marinate for 2-3 hours in,
3parts orange juice, 1 part lime juice, keep rinds in marinade and cooking.
Salt, 3 cloves garlic, 2 Bay leaves and Cumin.
Drain juice and everything else goes into the dutch oven, add in a quartered onion
I use enough bacon grease and lard to just cover the meat, and cook for 2 hours or tender over medium heat.
Then I switch to high heat to crisp the pork.
Salt the pork well as you pull it out of the oil.