Mix together the grated carrot, shredded cabbage, cilantro and sesame seeds. In a small bowl, whisk together (or shake in a small jar) the dressing ingredients - oils, vinegar, soy sauce and honey. Pour over the slaw and mix through. You can make this a little ahead and chill.
For rest of sandwich
Mix together the mayo and wasabi and set aside.
Warm the oil in a skillet large enough for the tuna steaks over a medium heat. Brush both sides with some teriyaki sauce and cook a minute or two on each side. As you turn, brush again with teriyaki and add some sesame seeds so they stick as you turn again. I'd suggest just a few minutes on each side in total so it is just seared, but you can cook more if you prefer.
Meanwhile, cut open the rolls and toast the inside if you like. Spread lightly with the wasabi mayo on both sides then put some slaw on the lower half. Top with the seared tuna and serve.
Notes
Note - if you want a deeper flavor and have time, you can marinade the tuna in around ¼ cup teriyaki sauce in a freezer bag, turning once or twice, for 30 min - 2 hours before cooking.