In a large bowl, combine the onion, breadcrumbs and milk. Let sit until the liquid is fully absorbed, about 5 minutes.

Gently mix the pork and bacon into the breadcrumb mixture.

Divide the mixture into 6 balls and press into 1-inch thick patties. Do not overwork the meat.

Preheat the grill to medium-high heat.

Oil the grill grates with the vegetable oil. Grill the patties over direct heat, covered, until the internal temperature reads 165°F, 5 to 6 minutes per side.

During the last minute of cooking, place cheese on the burgers.

Serve on toasted buns and desired toppings.