Mix all the marinade ingredients in a bowl. Place the tuna fillets in the bowl or in a strong sealable plastic bag and pour the marinade over the tuna. Marinate for as long as possible, but at least 25 minutes. Remove the tuna from the marinade and carefully pat dry with kitchen paper. Grill the tuna for a maximum of 1 minute per side on the grid of The Bastard and turn it over halfway through to create a nice grill pattern. Season with a little black pepper and serve with a wedge of lemon. TIP 1: Grill the lemon wedges too. TIP 2: It is better to put raw tuna back on the grill than overcooked tuna, which is a real shame.