Place ginger, reserving 1 tbsp, vinegar, wasabi powder, and mirin in a blender or food processor. Blend on high, while slowly dribbling in oil
In a bowl, mix 1/4 cup of the vinaigrette with the tuna. Add the green onion, the sesame seeds and the reserved, finely chopped pickled ginger, mixing until combined
Season with salt and pepper. Place the tuna on bread. Top with avocado, pea sprouts and the remaining bread or roll.
TIPS:
The vinaigrette will keep in the fridge for 1 week.
