• Heat a large, dry cast-iron skillet over high heat. Place the onions, cut-side down, into the skillet. Cook until charred, about 5 minutes. Then, flip and cook for an additional 2-3 minutes until charred. Once done, pull the onion halves apart and place them in the bottom of a 7-quart slow cooker.
• Heat a separate small pan over medium-high heat—avoid cast iron, as it burns the spices too quickly. Cook the anise seeds, stirring constantly until they're dark brown and fragrant, about 2-3 minutes. Transfer the mixture from the pan into a small bowl.
• Add the cinnamon, coriander, and cloves. Cook, stirring constantly, until the spices are fragrant and have darkened, about 1-2 minutes. They burn quickly, so watch them closely. Transfer to a separate small bowl.
• Transfer the toasted anise seeds to a cutting board. Use the edge of a sturdy drinking glass (or a mortar and pestle) to crush the seeds. Add the crushed seeds, along with the coconut sugar, red pepper flakes, and sea salt, into the bowl with the remaining toasted spices.
• Cut the large fat cap off the pork. Rub the spice mixture evenly over the rest of the pork, covering evenly.
• Sprinkle the garlic, ginger, fish sauce, and lime juice over the onions. Place the spice-rubbed pork on top.
• Cover the slow cooker and cook on low for 8-10 hours.
• Once cooked, remove the pork to a cutting board. Then, remove the onions and set them aside separately for later use.
• Shred the pork with two forks, then return it to the slow cooker. Toss so it coats in all the juices. You will have a lot of juice left over—that's normal.
  

To Make The Sauce:

• Heat a cast-iron skillet over high heat. Place the jalapeños into it, cut-side down, and cook until charred.
• Add the charred jalapeños, along with the ginger and lime juice, into a small food processor (mine is 3 cups). Pulse until the jalapeños are puréed.
  
• With the food processor running, stream the olive oil in until the mixture thickens.
• Add in a pinch of salt, along with the cilantro and mint. Pulse until the herbs are broken down.

To Assemble The Sandwiches:

• Spread a 1/2 tablespoon of sauce on each side of the bun—about 1 tablespoon total per bun. Then, divide the pork between the buns, followed by the cooked onions and a sprinkle of bean sprouts.