2) Place the cooled mixture with the egg yolks and 1 tsp salt in the jar of a blender and blend for 30 seconds. With the blender on, slowly pour the melted butter through the opening in the lid. Add the remaining tarragon leaves and blend only for 1 second.
3) If the sauce is too thick, add another 15ml of white wine to thin. Keep at room temperature until serving.
4) Season the steaks liberally with salt and coarsely ground black pepper on both sides. Heat a thin layer of olive oil in a large saute pan over high heat until it's almost smoking, then sear the steaks on each side for 1 minute.
5) Lower the heat to low and cook the steaks for about 7 to 10 minutes, turning once, until very rare in the middle. Remove to a plate, cover tightly with aluminium foil and allow to sit for 10 minutes. Serve with the bernaise sauce on the side.
* Cook's Note: To make the sauce in advance, prepare an hour before serving and allow it to sit in the blender. Before serving, add 1 tbsp of the hottest tap water and blend for a few seconds.