Note: This will make more pork than you need. Pork can be stored in refrigerator for up to 5 days in a sealed container.
- For the Pickled Red Onions
- 1 medium red onion, sliced about 1/8th-inch thick from pole to pole
- 1 cup distilled white vinegar
- 2 tablespoons sugar
- 1/4 cup water
- 1/2 teaspoon kosher salt
- pinch red pepper flakes
- 1 bay leaf
- 2 medium cloves garlic, thinly sliced
- For the Pork
- 3 pounds pork shoulder, trimmed of skin and gristle, cut into 3-inch chunks
- 2 cups pork fat (or vegetable oil)
- Kosher salt
- 6 cloves garlic
- 2 bay leaves
- 1 tablespoon whole cumin seed
- 1 teaspoon red pepper flakes
- 1/2 cup sugar
- For the Sriracha Mayonnaise
- 1 to 4 teaspoons sriracha (to taste)
- 1/2 cup mayonnaise
- 1 bunch cilantro, leaves and tender stems only
For the pickled onions: Place onions in a heatproof non-reactive container. Heat vinegar, sugar, water, salt, pepper flakes, bay leaves, and garlic cloves over high heat until boiling. Pour boiling brine over onions. Cover with a small plate to submerge onions. Let sit until cool.
Meanwhile, cook the pork. Place pork, fat, salt, garlic, bay leaves, cumin seed, and red pepper flakes in a heavy-bottomed Dutch oven or stock pot. Add enough water to cover. Bring to a boil, reduce to a simmer, and cook until pork is falling apart, about 90 minutes. Let cool for 30 minutes.
Preheat broiler to high. Remove pork from liquid and roughly chop. Toss with sugar and season with salt and pepper to taste. Broil, stirring every few minutes until browned and crispy throughout, 10 to 15 minutes total. Set pork aside.
Combine sriracha and mayonnaise in a small bowl.
Split sandwich rolls and toast. Spread spicy mayonnaise on each side of bread. Top with pork, pickled onions, and cilantro. Close sandwiches, cut as desired, and serve.