In a 14 inch deep camp Dutch oven over a bed of coals, brown cubed pork, stirring to cook all cubes.
When browned, add onion, celery, green onion, bell pepper, and garlic.
Stir and cook about 10 minutes, until vegetables are soft.
Push mixture to one side of the oven.
Add 2 tablespoons oil to pan juices. Stir in flour to make roux.
Roux is a thickening agent created when mixing flour and oil.
Stir until flour mixture is light tan.
Add 4 cups water and stir to make a smooth gravy, stirring in the meat mixture.
Bring to a boil and stir until mixture thickens. If mixture is too thick, add more water.
Add tomatillos and green chiles. Add salt to taste.
Simmer for 30 minutes to blend flavors and tenderize meat.
Serve with fresh tortillas.