I tried a new way (TO ME) of cooking Sirloin Steaks ,last evening. I done the steaks on a very hot griddle pan after oiling the steaks and adding salt and ground pepper. i cooked for about 2 mins each side, removing and placing them on plates , to settle for 3 mins in the warm compartment of the stove ,its just warm enough to keep the steaks warm with no further cooking. I had previously put into a medium heat oven, large slices of RED onions coated in oil for between 25-30 mins. I made up a sauce earlier of DIJON mustard and BUTTER. the make up for the sauce was 4 dessert spoons of BUTTER .add 2 teaspoonful of DIJON mustard in a bowl and mix till a good consistency is achieved. scoop the mixture onto a piece of cling film and roll into a sausage shape. place the mixture into the fridge and let set. when steak is served cut a piece of the sauce and place on top of the hot steak to melt over the steaks :yho::yho::yho: ENJOY music.
Actually above is a great method also. But of course the Grill is the best, in the winter when you don't want to venture out to the deck the cast iron and oven is the way. And honestly I love simple good steak just salt and pepper. Yum. And sorry, I prefer a good prime rib steak over sirloin any day. But your mustard butter stuff sounds interesting.
