Rinse and chop onion, potatoes, cilantro, and tomatillos, if using. Set cilantro and potatoes aside. Remove pork from the can, reserving canned juices, and break it up on a cutting board.
Heat oil in a large pot over medium-high heat. Add onions and sauté until soft. Add cumin seed and stir until seeds are toasted.
Reduce heat to medium and add pork. Cook 5 minutes until the pork is heated through. Add tomatillos, if using, and cook another 2-3 minutes.
Add salsa verde, chicken broth, reserved canned juices, chiles, oregano and potatoes to pot. Cover and simmer over medium-low heat for about 30 minutes or until potatoes are tender.
Portion into bowls and garnish with chopped cilantro and red chile salsa.