For the tahini sauce combine all of the ingredients in a bowl and reserve in the fridge until needed.
Prepare your barbecue for direct cooking over a high heat (230 to 290°C).
Brush the zucchini and the beef with olive oil and season generously with salt and pepper.
Barbecue the beef fillet over direct high heat for 2 minutes on each side for a rare result, 3 minutes each side for a medium rare result. Remove the beef from the barbecue and set up your Weber Q with a convection tray and trivet for indirect cooking. Place the beef onto the trivet and roast over indirect medium heat for 10 to 12 minutes, or until cooked to your liking. For rare, the final internal temperature is 49°C, for medium rare 54°C, keeping in mind the internal temperature will continue to rise 3-6°C while resting. Remove the beef from the barbecue and allow to rest for at least 5 minutes.
Whilst the beef is cooking, barbecue the zucchini batons over direct high heat for 8-10 minutes or until tender and slightly charred. Place in a bowl while still hot and dress with 2 tablespoons of the tahini sauce, tossing to coat.
Spread the rest of the sauce onto a round platter. Arrange half of the dressed zucchini onto the sauce. Slice the meat into medallions and place over the zucchini. Top with the remaining zucchini and sprinkle over sesame seeds and mint.