Heat oil in a pot over high heat until nearly smoking. Add pork cubes in a single layer. Let sear until brown on one side, 4 to 5 minutes. Mix, turning pieces over to brown on the other side, 4 to 5 minutes.

Add onion and 1/2 teaspoon kosher salt. Cook and stir until onion is translucent, about 4 minutes. Add oregano, cumin, coriander, and cayenne; cook and stir until seasonings are fragrant, about 2 minutes. Reduce the heat to low.

Cut tomatillos into quarters. Place into a blender with chili peppers, garlic, and cilantro. Add chicken stock. Pulse on and off until pieces start to break down, then blend until mixture has liquefied, about 30 seconds.

Stir sauce into pork mixture. Add 1 teaspoon kosher salt and bay leaf. Increase the heat to high and bring to a boil. Reduce the heat to low and maintain a slow but steady simmer for about 1 hour.

Add potatoes, remaining 1/2 teaspoon kosher salt, and black pepper. If the mixture has reduced to where potatoes are not immersed, add more broth to cover. Simmer until pork and potatoes are tender, 45 minutes to 1 hour.