Start by making the flavorful glue that ties this dish together. Melt the butter in a medium saucepan over medium heat. Once it starts to sizzle, add the onions and cook until they’re soft and fragrant. Toss in the garlic and give it a quick stir until aromatic.
Add in the cider vinegar, water, and ketchup, stirring to combine. Sprinkle in paprika, chili powder, and mustard, followed by the sriracha and Worcestershire sauce. Simmer gently for about 15 minutes, stirring occasionally. It’ll thicken up into a luscious sauce that’s perfect for coating the chicken.
Place the chicken thighs in a large bowl. Drizzle them with olive oil, then sprinkle on salt and black pepper. Rub everything together so the seasoning sticks to every piece. This step ensures a good base flavor before the sauce takes over.
For the grill, heat to medium-low (you want the chicken to cook slowly for juicy results). Place the thighs on the grill, smooth side down. Cook for 3-4 minutes on each side, flipping occasionally. Use a meat thermometer to check for an internal temperature of 165°F.
If baking, preheat your oven to 375°F. Arrange the chicken on a baking sheet and bake for about 25-30 minutes, flipping halfway through.
Once your chicken is done, transfer it to a large bowl. Pour your warm BBQ sauce over the top, ensuring every piece is evenly coated. For an extra sticky finish, return the chicken to the grill or oven for a few more minutes.