Take the steak out of refrigerator about 1 hour before cooking. Prepare the steak by cutting off any excess fat around the edges.
Using mortar and pestle grind 3/4 of beef stock cube. Add green and black peppercorns to the mortar and coarsely grind.
Spread the spice mixture over the large plate making an area roughly equal to size of the steak.
Put the steak between two pieces of plastic wrap and tenderize it with mallet. Gently beat the steak to about 1/2″ (10-12 mm) even thickness.
Lay the steak down over the spice mixture and press down. You want spice mixture only on the bottom side of the steak!
Drizzle little olive oil and evenly coat the top of the steak. Set aside for about 10 minutes.
Cut shallots and assemble the rest of ingredients: butter, cream, cognac, dry parsley, Worcestershire sauce and Demi-glace.
Over medium high heat (7.5 out of 10) preheat heavy non stick skillet up to 150ºC (300ºF).
With oiled side down place the steak in the hot skillet and brown for 2.5 to 3 minutes. At 2 minutes time mark add the butter and shallots beside the steak. As the butter melts lift the skillet and tip it from side to side making the butter flow around the steak.
At 2.5 or 3 minute turn the steak over to the seasoned side, drizzle Worcestershire sauce around the steak.
Pour cognac on top of the steak and ignite with match to create flambé, make sure to stay back when you doing it.
After about 1.5-2 minutes of cooking time transfer the steak to the plate.
Add Demi-glace, cream and dry parsley to the skillet, mix with heat proof silicone spatula, turn off the heat. The residual heat from the hot skillet will be sufficient to thicken the sauce after about 1 minute of cooking.
Plate the steak, pour over the sauce, garnishing with chopped fresh parsley and serve immediately!