In a large skillet, heat a drizzle of oil over medium-high heat. Add the ground beef, cooking until browned and crumbled, about 5–7 minutes. Drain excess grease, then transfer the beef to a stock pot. Stir in the diced tomatoes, brown sugar, onion powder, chili seasoning, tomato paste, ground cumin, chili powder, black beans, and pinto beans. Bring to a boil, then reduce heat and let simmer for about 1 hour, stirring occasionally.

While the chili is simmering, shape the remaining ground beef into four equal patties, about ¾ inch thick. Season both sides with salt and pepper. Create a slight indentation in the center of each patty.

Preheat your grill or a skillet over medium heat. Add the burger patties and cook for about 7 minutes on one side until seared. Flip and cook another 7 minutes, or until desired doneness. Place a slice of American cheese over each patty during the last minute.

On the bottom bun, place a patty, spoon about ¼ cup of chili over it, drizzle with queso, add crispy onion strings, and cap with the top bun.