Start with the sauce: 1/3 gin (or sake), 1/3 Mirin and 1/3 soy sauce. Bring to the boil and reduce till half is left.
In the meantime put the griddle pan on.
First some thin slices of fennel go in, about 1 min. on each side, till nice and just soft enough.
Then the lightly oiled tuna for 2 mins.
Serve with a spoonful of hummus and some leek shoots.