Bring rice, matcha, 600ml cold water and a pinch of salt to the boil in a saucepan over high heat and boil for 2 minutes, stirring occasionally,. Cover with a lid, reduce heat to low and simmer without uncovering for 8 minutes. Remove from heat. Combine 50ml vinegar and sugar in a bowl, drizzle over rice, cover and set aside for 5 minutes. Tip rice onto a tray and spread out to cool briefly.
Whisk grapeseed oil, soy sauce, garlic and remaining vinegar in a bowl.
Toss cucumber, pickled ginger, spring onion and a little dressing in a bowl to coat.
Serve matcha rice topped with trout, cucumber salad, sesame seeds and extra dressing.
Note Matcha, a powdered green tea, is available
from Japanese supermarkets.