Pat your pork tenderloin dry with paper towels and slice it crosswise into approximately 3-inch pieces. Season all over with salt and pepper.
Heat 1 tablespoon oil in a Dutch oven (or saucepan) over medium-high heat. When hot, add the pork pieces and brown them on all sides. (This will take about 6-8 minutes, peeps.) Remove the pork from the Dutch oven and set aside.
Reduce the heat to medium and add the remaining tablespoon oil to the Dutch oven. When hot, add the onions, garlic, jalapeño, and green chilies. Cook for 3 minutes until the onions become translucent and the garlic is fragrant. Add the cumin, oregano, and cayenne pepper and cook for 2 minutes until the spices are nice and toasty.
Return the pork to the Dutch oven, along with the pinto beans, chicken stock, beer and hot sauce (if using). Bring to a boil, lower to a simmer, cover and cook for 40 minutes.
Remove the pork pieces from the liquid and place them on a cutting board. Shred the meat using two forks.
Using a slotted spoon transfer 1 cup of beans to a blender or food processor. (Yes, there will obviously be some onions and peppers in there as well. That’s a good thing.) Pulse until relatively smooth. (This puree will help thicken the chili, but you can skip this step if you prefer a soupier consistency.)
Return the shredded pork and the bean puree to the Dutch oven. Simmer the chili, uncovered, for 15 minutes until slightly thickened. Turn off the heat and stir in the apple cider vinegar. Season with salt to taste.
Ladle chili into bowls and serve with toppings of your choice.