For the burgers, remove the skin from the tuna and any sinewy bits. Dice the tuna relatively small, approx ¼in/1/2cm, then put in a bowl with the soy sauce and miso paste. Mix well and form in to 8 to 10 burgers, pressing them together into flattened balls. Refrigerate for around 20mins until ready to use.
For the pancakes, mix together the dry ingredients in a bowl (flours, baking soda, baking powder and salt). Separately whisk together the milk and egg. Add the egg mixture to the flour mixture and whisk so that it is smooth. Add the water to thin it slightly. Remove the outer leaf from the scallions and slice, including most of the green part, then mix into the batter.
Mix together all of the sauce ingredients together until combined and set aside.
Grill the burgers for a few minutes each side until they are cooked to your preferred level of doneness - as long as you have good quality tuna, you can have them pink in the middle, but you can also cook right through. If you don't want to or can't grill them, you can also pan-fry them in a little vegetable oil.
Meanwhile (if you are able), warm a heavy-based skillet/frying pan or griddle over a medium heat and lightly oil it. Drop spoonfuls of the pancake mixture onto the warm pan and cook until they bubble (a minute or two) then flip over and cook another minute on the other side. Keep warm either in a low over or covered in a dish cloth while you cook the others in batches.
Note - If you can't cook the pancakes at the same time as the burgers, then cook the burgers first and keep warm until ready.
When ready, make up 'burgers' with one or two pancakes, a tuna burger and a few drizzles of the sauce. Good served with grilled asparagus or other grilled vegetables as well.