Seared Sesame Tuna with Sweet Soy on Greens

Combine soy, mirin, sugar and rice vinegar in a saucepan and simmer for 5 minutes. Allow to cool. Cut green beans in half lengthwise (if using snow pease or broccolini, cut into strips). Coat tuna steaks in ¼ cup soy mixture, reserving the rest for serving, and coat tuna on both sides with sesame seeds. Heat 2 tablespoons oil and 1 tablespoon sesame oil in a frypan until very hot. Add tuna and sear quickly for 1 minute on each side until sesame seeds are golden – the tuna needs to remain rare in the centre. Allow to rest. Wipe out pan with paper towel, add 2 tablespoons oil and remaining sesame oil and sauté garlic and beans for 1 minute, add mirin and spring onions and stir fry until snow peas are just tender. Cut tuna into slices and serve on a bed of beans, drizzled with a little reserved soy mixture.