First: make the onion rings. In a medium saucepan over medium-high heat, add canola/vegetable oil about 2" high. In a small bowl, combine the flour, salt and pepper. In another small bowl, add the buttermilk.
A handful of onion rings at a time, dredge the rings in the flour, then dip the rings into the buttermilk, allowing the excess to drip off, then dredge again in the flour.
Working in batches, add onion rings to the hot oil and cook for about 2 minutes or until golden. Transfer to a paper towel and continue this process until all onions are cooked.
For the sliders; Gently form the ground beef into 6 equal sized patties. Very lightly drizzle each side with worcestershire sauce and sprinkle both sides with salt and pepper.
Heat a skillet or preferably a grill pan over medium-high heat. Once the pan is hot, add the sliders and cook for about 4 minutes, flip over and cook for another 3 minutes. Add cheese, cover, and cook for 1 more minute.
Serve your cheeseburger sliders on lightly toasted slider buns topped with mayo, ketchup and an onion ring! Enjoy!