Heat one tablespoon of coconut oil in a large skillet.

Season sirloin with salt and pepper and add it to the pan once the coconut oil has melted.

Cook until browned and then flip and cook again until browned. Remove to a bowl and set aside for now.

In the same skillet, add the remaining tablespoon of coconut oil.

Once melted, add onion and mushrooms and cook until the onion has softened and the mushrooms are browned.

Add beef stock, coconut milk, and dijon mustard and whisk everything together.

Add the meat back into the skillet and bring to a boil. Boil for 3 to 5 minutes, just until the meat is completely cooked through and the sauce has thickened slightly. If you want a thicker sauce, whisk 1 - 2 teaspoons of arrowroot powder into about 1/4 cup cold water and pour into the pan. Whisk everything and cook just until thickened.

Sprinkle parsley on top before serving.