Heat oil in a large heavy bottomed pan (like a dutch oven) on your stove top, over medium-high heat.
Sprinkle salt and pepper over all sides of the pork roast. Place the roast in the heated oil and brown, turn the roast over on each side until each side is browned, about 2 minutes per side.
Add the onion, and garlic. Cook for 3 minutes to get the flavors to start releasing from the onion and garlic.
Add 5 cups of broth, green chilis, tomatillo salsa, cumin, Mexican oregano, and a pinch of ground cloves to the pan.
Lower heat to a low simmer and let it simmer for 1 hour with the lid on the pot, stirring occasionally. After about 1 hour, check if the roast is done in the middle and tender. If not, let pork cook another 20 minutes and check again.
Remove the roast from the broth. Using two forks, shred the roast into bite size chunks. Set pork aside.
Add the potatoes to the chili broth and cook for 20 more minutes, until potatoes are tender.
In a separate bowl mix together the masa (a few tablespoons) and 2 cups of chicken broth together until smooth. Stir into the chili. Add the shredded pork roast back to the chili. Cook until thickened, about 20 minutes.
Serve with a drizzle of Mexican crema (or sour cream) and cilantro, if desired.
