Step 1Place the mayonnaise, ginger, wasabi, onion and pepper in a food processor and blend to mix. Set aside.
Step 1Place the cabbage in a large bowl. Blend the vinegar, oil and onions in a food processor, then pour over the cabbage and toss to coat.
Step 1Marinate the ahi steaks in the soy sauce 30 seconds on each side. Heat a grill (or a grill pan that has been sprayed with cooking spray) to high heat.
Step 2Reduce the heat to medium-high and sear for 1 minute. If you want to have crisscrossing grill marks, rotate each steak 90 degrees and continue to cook for 1 minute, then turn.
Step 3Repeat the process, cooking about 2 minutes to sear, and rotating if desired. The steaks will be rare in the middle.
Step 4Toast the buns and spread both sides with the mayonnaise mixture. On the bottom of each bun, place an ahi steak, pile about half a cup of slaw on top, then cover with top half of bun.