Preheat a nonstick griddle or grill pan to high heat.

Cube tuna into bite-size pieces.

Place tuna in a food processor and pulse until coarsely ground to the consistency of ground beef or turkey.

Transfer the ground tuna to a bowl.

Combine the ground tuna with chopped garlic, minced gingerroot, dark soy sauce, chopped scallions, finely chopped red bell pepper, sesame oil, steak seasoning, and black pepper.

Form the mixture into 4 large patties, about 1 1/2 inches thick.

Drizzle both sides of the patties with light-in-color oil.

Cook the tuna burgers for 3 minutes on each side for rare, or up to 6 minutes on each side for well done.

Preheat broiler.

In a medium nonstick skillet over high heat, sauté the chopped shiitake mushrooms for 2-3 minutes in 1 tablespoon of light oil.

Season the sautéed mushrooms with salt and pepper.

Open up the sesame kaiser rolls and lightly toast them under the broiler.

Spread mango chutney on the bottom half of each toasted bun.

Top the chutney with a tuna burger, sautéed shiitake mushrooms, and red leaf lettuce.

Spread wasabi mustard or sweet hot mustard on the top half of the bun and set it in place.

Serve the burgers with exotic chips and pickled ginger, if desired.