In a small bowl, mix together the mayo, ketchup, sweet chili sauce, garlic powder, and sriracha until combined. Set the boomb boom sauce aside.
Grill the hamburger patties in a skillet over medium-high heat to your desired doneness. (Medium > 7 to 8 minutes, Medium-Well > 9 minutes) A couple of minutes before the burgers are done, place a slice of cheese on top of each patty and allow it to melt.
Stack the burger patties on the bottom burger bun. Top with coleslaw and then the onion rings.
Slather Boom Boom Sauce on the cut side of the top bun and then place it on top of the burger. Serve immediately.
Notes
If you don't want a double burger, you can absolutely make this a single patty burger.
I usually get frozen onion rings and cook them in the oven or my air fryer.
There is enough sauce for 3-4 burgers, or save the extra to dip your fries in.