Stir the chili powder, smoked paprika, cayenne pepper, salt and pepper together in a small bowl. Get out the pork shoulder and rub that mixture all over it. Then heat the olive oil in a large Dutch oven over medium high heat. Brown the pork shoulder for about 2 minutes on each side to bring out the flavors of the spice rub. Pour in the lime juice, lime zest, tequila, chicken stock, cilantro and onion. Let it come to low boil, then cover the pot with its lid. Reduce the heat to a simmer and let it go low and slow for 6 hours.

When it is done, remove the pork shoulder from the pot onto a large cutting board. Use two forks to shred the meat off of the bone and fat back. Transfer it to a bowl and pour a cup of the cooking liquid on the shredded pork. Mix it together. Then assemble the sandwiches! Toast the buns, then pile on the pork, a couple of slices of avocado and a couple of spoonfuls of salsa. Enjoy!