For the turf: Whisk together the soy sauce, cilantro, honey, ginger, sesame seeds, chile flakes, garlic and spring onions in a bowl. Stir in the sesame oil.
Using cocktail sticks, pin the bottom of the beef fillet to create a round shape (quicker than trussing with butcher's knots!). If already nicely round, the cut may not require this step.
Place the fillet in a freezer bag and pour over two-thirds of the marinade, gently rubbing it into the meat. Marinate in the refrigerator for at least 2 hours.
Preheat the oven to 350 degrees F.
Remove the meat from the marinade and gently pat dry. Set aside for 5 minutes to warm up a bit.
Heat a nonstick frying pan or griddle until hot. Sear the beef for 1 1/2 minutes on each side. Transfer to a baking sheet and drizzle with oil. Roast for 5 to 8 minutes for medium rare.
Remove the fillet to a cutting board, reserving the pan juices for the sauce. Tent with foil and let rest for 10 minutes.
For the surf: Heat the butter over high heat in a large frying pan. Add the garlic and the 1 tablespoon ginger, and saute until fragrant. Add the squid and cook until the legs curl up and the bodies are white, 2 minutes. Season with salt and pepper. Off the heat, stir in the cilantro, lemon zest and a squeeze of lemon juice. Remove the squid to a plate and cover to keep warm.
To make the sauce, add the reserved meat juices and the remaining marinade to the calamari pan; cook for 8 minutes. Add the beef stock and simmer until reduced slightly. Stir in the remaining 1 teaspoon ginger and then strain the sauce through a sieve into a serving jug.
Carve the fillet and arrange on a board. Arrange the calamari on the board and garnish with cilantro. Serve with sauce alongside.