Finely chop the hatch chilies and set aside.
Add the tomatillos to a small food processor and pulse several times until finely chopped. Set aside.
Heat the olive oil over medium high heat in a large dutch oven or heavy bottomed pot. Add the cubed pork, salt and pepper and cook, stirring occasionally until the pork is browned on all sides.
Add the bell pepper, onion and garlic and cook, stirring several times, until the vegetables are tender and slightly translucent, about 5 minutes. Stir in the cumin and chili powder and cook for one minute. Stir in the chopped chilies, tomatillos and chicken broth. Turn the heat to high and bring to a boil, reduce heat to a simmer and stir in the black beans and great northern beans. Simmer for 30 minutes with the lid slightly askew, stirring occasionally.
Season to taste with salt and pepper. Serve chili plain or over cooked rice or noodles, with an assortment of toppings such as sour cream, chopped green onions, cilantro and shredded cheddar or monterey jack cheese.