Make the barbecue sauce. Mix all the barbecue sauce ingredients in a saucepan. Bring to a boil and simmer for 3 to 5 minutes or until thickened. Set aside and let it cool.
Make the Coleslaw. Place the shredded cabbage and carrot in a medium-size bowl. Add chopped onion and lemon zest. Mix all the Coleslaw dressing ingredients in a small bowl until well blended. Pour the dressing on the vegetables and toss until combined. Refrigerate until ready to use.
Make the BBQ Pork Patties. In a medium-sized bowl, add all the pork patties ingredients and mix just until combined. Divide into 4 for regular size patties or 3 for thicker patties. Shape into round patties about 4 to 5 inches wide. Place them on parchment paper. Place in the freezer for 20 to 30 minutes before grilling.
Grill the BBQ Pork Patties. Preheat the grill to 450°F. Grill the patties on medium-high heat for about 5 to 7 minutes on each side. Brush with barbecue sauce (optional).
Assemble the burger. Grill or toast the brioche buns (optional). Slather the sriracha mayo on the base bun, then place the burger patty. You can add and slather the homemade barbecue sauce on top of the burger patty (optional). Add the coleslaw, then the top part of the brioche bun.