In a large mixing bowl, combine the coleslaw mix, minced onion, Duke's mayonnaise, apple cider vinegar, sugar, celery seed, garlic powder, and pepper. Stir until all ingredients are evenly coated and the mixture is creamy, then cover and refrigerate to allow the flavors to meld for at least 20 minutes.

In a medium saucepan, brown the ground beef over medium heat for about 5-7 minutes until fully cooked. Stir in the chili seasoning, water, minced onion, and ketchup, mixing thoroughly. Allow this mixture to simmer for 10-12 minutes until it thickens slightly.

Divide the ground chuck into four equal portions, shaping them into thin patties, about ¾ inch thick. Season each side generously with steak seasoning. Heat a skillet or grill over medium-high heat, and cook the patties for 6-7 minutes per side, or until they reach your preferred doneness.

Once the patties are ready, take the bakery buns and spread yellow mustard on the inside of each bun. Start with a burger patty on the bottom half, adding optional melted cheddar cheese, followed by a generous scoop of the hotdog chili. Top with a helping of the creamy coleslaw and diced onions. Cap off your creation with the top bun, and press down gently to secure everything together.