In a medium bowl, whisk together mayonnaise, apple cider vinegar, and sugar until smooth. Add the shredded green cabbage, purple cabbage, and carrots, tossing until everything is evenly coated. Cover the bowl and refrigerate for at least 30 minutes.

In a separate bowl, combine mayonnaise, sour cream, milk, and minced garlic. Whisk until smooth and creamy, seasoning with salt and pepper to taste. Set aside.

In a small saucepan over medium heat, combine honey, minced chipotle peppers in adobo, and ketchup. Stir and bring to a gentle simmer, cooking for 5-7 minutes until the sauce thickens slightly.

Flatten the chicken thighs to an even thickness. Season with salt and pepper, then grill for 5-7 minutes on each side until cooked through.

Remove the chicken from the grill and toss in the warm honey chipotle sauce until well-coated.

Melt butter in a skillet, then toast the brioche slider buns until golden brown.

On each toasted bun, place a piece of the honey chipotle chicken, top with coleslaw and drizzle with garlic sauce. Close with the top bun.