For slaw, mix ingredients together in a large bowl and refrigerate until ready for use.
For chili, brown ground beef in a skillet (ad) over medium heat, then add chili seasoning, water, onion and ketchup. Simmer for 10 minutes until meat is tender and chili is thickened.
For burgers, pat ground chuck into 4 equal (thin) patties and sprinkle with steak seasoning. Fry in (ad) over medium heat until cooked throughout. Top with cheddar cheese until it melts.
To assemble burgers, spread yellow mustard on inside of buns. Place hamburger patty on bottom bun. Top with chili, then add slaw and onions. Close with top bun.
Insert a steak knife (ad) into top bun to hold burger together.