Heat olive oil in a large skillet over medium-high heat.
Season pork tenderloin with salt and pepper. Sear in the skillet until all sides are browned, it won't be cooked through at this point. Once seared, place the pork on the bottom of the slow cooker.
Mix together flour and dry seasonings. Add to the slow cooker on top of the pork.
In the same skillet that you seared the pork in (do not clean it out), add the onion, peppers, and garlic. Saute until charred and tender, stirring occasionally.
Add the charred onions and peppers to a blender along with both cans of green chiles and their liquid. Puree for 10-15 seconds or until mostly smooth, a few small chunks are fine.
Pour chile mixture, enchilada sauce, chicken broth, and cilantro over the pork in the slow cooker. Stir together.
Cook on low all day for the best flavor, or at least 6-8 hours. Before serving, remove pork and shred then return to the pot and stir.
Serve with tortillas, shredded cheese, sour cream, and cilantro for garnish if desired. Enjoy!