Dice the onion and brown in a pan then when browned add butter. Heat oil to fry in.
Fry the French fries and move them to a paper towel to absorb excessive amounts of oil. Salt them. Do these in batches.
When the butter is melted add the flour. Stir and let the flour cook for 3-4 minutes.
Add the stock and spices. Whisk well no lumps. Add the worechestershire sauce mustard powder, and Heinz ketchup. Whisk till all ingredients are incorporated into the gravy.
When the gravy coats a spoon its thick enough. Add those grilled burgers, to the gravy, and simmer. Cover and turn off heat when the grilled patties are reheated throughout. Cover and set aside till all your fries are cooked. This will allow the smokey flavour to mingle in your gravy.
Serve with the gravy atop the fries. I hope you enjoy
