I am taking liberty here with the term "nigiri," which is typically a slab of fish over rice, and is sometimes wrapped in a strip of nori, the seaweed used to wrap sushi rolls, aka maki sushi. This oil free protein packed recipe has marinated tofu stuffed with a rich walnut shitake butter, held together with a strip of nori.
-Meanwhile, in a 9x12 baking pan, combine tamari, rice wine, mirin, ginger and garlic
-Place tofu on cutting board with thinner side vertically facing, long side facing up
-Cut into 8 equal slices, and lay in single layer in marinade baking pan
-Let marinate 10-15 minutes
-Prepare shitake walnut butter
-Pulse shitake mushrooms in a food processor or mini chopper with slice blade until finely chopped, then place in small bowl
-Process walnuts until they become a paste, and add to shitake
-Add 1/2 of the scallions, and mix to combine
-With a spatula, carefully turn tofu slices over in marinade
-Spread shitake walnut mixture evenly over 4 of the 8 tofu slices
-Use the remaining 4 slices tofu to top the shitake walnut butter making a "sandwich"
-Wrap each "sandwich" with one strip of nori, centered crosswise
-Bake for about 30 minutes, or until tofu is browned, and garnish with remaining scallions
Recipe Notes
*If you do not have a tofu press, slice tofu as above, place slices on a cutting board tilted to drain in sink, and top with a second cutting board, and a pot of water to weight it down. Let drain for 15 minutes, then continue with above directions