In a large frying pan, heat the schmaltz over high heat until
very hot, add the seasoned beef strips and sauté until the meat is
browned all over, in the same pan flambé the beef carefully adding
the cognac to the pan, the alcohol will burn off, this whole
process should take only a minutes or so then place in a dish to
the side and keep warm.
Add the butter to the pan over medium heat, add the shallot and
garlic then sauté for 1 minute, then add the mushrooms and continue
to cook until soft.
Stir the mustard into the pan then add the stock and boil until
reduced by half then stir in the sour cream and boil together until
rich and creamy.
Gently fold the beef through the sauce, check the
seasoning-adding a squeeze of lemon and serve straight away.
Sprinkle with snipped chives before serving.
Freshly cooked fettuccine and extra dollop sour cream.
Note: Fillet tails or sirloin can also be used for this