Step 1

Drain the fat, but don't clean the pan: While your steaks are resting, pour off the fat from cooking and any aromatics that were cooked with the steak, but do not wipe the pan clean.

Step 2

Cook the shallot and thyme: Return the pan to medium heat and add the shallot and thyme and cook until fragrant and the shallot has softened.

Step 3

Deglaze the pan: Add the wine or broth and scrape the browned bits off the bottom of the pan with a wooden spoon or whisk. Cook until the liquid reduces slightly, about 1 minute.

Step 4

Add the mustard and butter: Whisk in the mustard and remove the pan from the heat. Vigorously whisk in the cold butter until thickened.

Step 5

Serve: Slice the steak and serve with the pan sauce.