For Pickled Red Onions:

In a medium pot over medium heat, combine all pickled red onion ingredients, except onions. Bring to a boil, add the onions and remove from heat. Let sit until cooled about 1 hour. Serve with sliders.

For Mustard BBQ Sauce:

In a small pot over medium low heat, whisk all the BBQ sauce ingredients together. Cook for 3 minutes or until hot and then remove from heat.

For Sliders:

Place a heaping tablespoon of pulled pork of the bottom of a roll. Drizzle with the barbeque sauce, top with some of the pickled red onions and then place the remaining roll halves on top. Repeat with remaining ingredients and serve.