Prepare the fillet of beef: cut off all fat and membrane, tie with butcher's string and shape into a log to hold its shape. Brush the meat with French mustard and sprinkle with herbs. Sear the meat on all sides in a frypan for a few minutes to prevent the juices escaping. Bake in a 200 degrees C oven until the desired doneness is achieved.
Meanwhile, peel the potatoes and cut into segments, place in a bowl, coat with olive oil, sea salt, pepper and tomato paste. Set aside.
Peel and cut the butternut and shape into rounds, coat with olive oil and season with salt and pepper. Set aside.
Peel another two small cream potatoes, cut into small pieces and boil until well done. Place the cooked potato in a blender together with a small amount of milk and puree to the desired consistency. In the same manner place all the infusion ingredients in a blender then add a small amount of prepared lime infusion to taste to the blended potatoes to taste.
Place the vegetables in the oven covered with foil and cook for approx. 25 minutes. Remove foil and bake for another 10 minutes to crisp.
Remove the beef when ready and set to rest, covered, for at least 10 minutes.
Place the spinach in hot boiling salted water for approx. 1 minute to wilt. Drain and serve on the plates.
Remove the string from the fillet and cut into thick slices, place on top of the spinach on each plate.
Place the roasted potatoes and butternut rounds and pipe the butternut rounds with the puree then sprinkle with dill tips.
Serve with red wine jus.
The infusion is also available as Lemon and Oregano dressing from Red Kellys / Tasmania. It's available at Woolworths. Dill tips are in the dry herb section. I also use my metal cookie cutter to get the same size rounds for the butternut. Use cream potatoes as some other varieties are too floury.