There should be enough fat left in the pan if you’ve just cooked a steak, but add a little more butter or oil if it needs it. Add the crushed black peppercorns and toast over a low heat for 1-2 minutes.
Add the shallots and cook for a few minutes until softening. Add the garlic and cook gently for 30 seconds or so until you can smell it, then add the thyme.
Add the brandy and, using a long match/lighter, carefully set it alight (see Know-how). Once the flames die down, let it bubble and reduce completely.
Add the stock, turn up the heat and bring to a simmer. Reduce by two thirds (about 8 minutes). Add the Worcestershire sauce and cream, turn the heat down and simmer gently for 5 minutes. Add the green peppercorns, then season to taste with salt.
