Trim overcooked meat and fat from the prime rib roast.

Chop the trimmed prime rib roast coarsely.

Chop 12 of the large onions.

Thinly slice the remaining 3 large onions and set aside.

Place the chopped prime rib and chopped onions into a heavy Dutch oven.

Add the madcity dale luv seasoning and barbecue sauce to the Dutch oven.

Using medium-high heat, bring the mixture to a low simmer for 50 minutes.

Stir the mixture well.

Remove the Dutch oven from heat and cover the mixture with the thinly sliced onions.

Garnish liberally with barbecue sauce.

Let the dish set for 5-10 minutes.

Serve a heaping spoonful on each bun.