Caramelized Onions:

1. Cut the onions in half, then slice them thinly.
2. Melt the butter in a large skillet, then add the onions.
3. Cook over low-medium heat until the onions are softened. About 15 minutes.
4. Then add the rosemary stems and bay leaves. Mix. Cook for about 20 more minutes, until the rosemary has wilted.
5. Once the rosemary has wilted, remove it and the bay leaves. You will likely have to remove stray rosemary leaves.
6. Stir in the balsamic vinegar, sugar, salt and pepper.
7. Continue cooking until the liquid is all gone, and the onions are caramel coloured and soft. Be very careful not to burn the mixture, so stir often.

Horseradish Cream Sauce:

1. Combine the horseradish, sour cream, Worcestershire sauce and Sriracha. I like to use a hand blender to make the sauce nice and creamy.

Putting it all together:

1. Add slices of cooked prime rib to a bun, add a scoop of caramelized onions and drizzle with the horseradish cream sauce. If you have gravy from the prime rib pan drippings, add that too…it’s SO good.
2. Serve immediately and enjoy!