Put the orange zest, tarragon, Pernod or Richard and 1 tbsp of the oil in a bowl and mix together.
Rub this mixture into the beef slices and marinate for 2 hours.
After 2 hours, scrape the marinade off the beef and retain for later use.
Season the beef lightly. Heat 2 tbsp of the oil in a frying pan and cook the beef over a high heat for 1 minute on each side. (This may need to be done in batches).
Remove the beef from the pan, place it on a hot platter and keep warm.
Add the marinade and any juices seeping from the beef to the frying pan. Add the remaining, oil, vinegar, spring onions, chervil, chives, olives anchovies, orange juice and segments, and tomatoes. Stir together, place over a medium heat and bring to boil. Season if necessary.
Divide the hot steak slices between 6 warmed plates and pour the sauce over the beef. Serve with new potatoes and vegetables of your choice.