Brush the tuna with the egg white. Scatter the seeds over a clean work surface or flat plate and roll the tuna in the seeds until covered all over. Season with salt and freshly ground black pepper, to taste.
Wrap the tuna very tightly in cling film to make a solid barrel shape. Transfer to the fridge and chill for two hours.
For the crisp-fried noodles (if you are making them), heat the vegetable oil in a deep heavy-bottomed saucepan until a breadcrumb sizzles and turns golden-browns when dropped in it. (CAUTION: hot oil can be dangerous - do not leave unattended.)
Deep fry the egg noodles for 1-2 minutes until crisp, remove with a slotted spoon and drain on kitchen paper.
For the dressing, blend the soy sauce, ginger, honey, sesame oil and lime juice together in a blender or food processor until smooth.
When you are ready to cook the tuna and the vegetables, heat both a pan and a wok until smoking.
Add vegetable oil to both the pan and the wok, place the tuna in the pan and cook for about 30 seconds on all sides.
For the vegetables, add all the vegetables to the wok, mix well and then add some of the dressing.
Serve the tuna on the vegetables, drizzled with the remaining dressing and topped with the crisp-fried noodles.