Preheat the oven to 350 degrees.

Place the tofu on a shallow plate and cover with the tamari, turning to coat both sides. Marinate for at least five minutes.

In the meantime, prepare the walnut crust but pulsing the walnuts, garlic and onion powder in a food processor until well blended and finely chopped. Place the walnuts in a thin layer on another shallow plate.

Remove the tofu from the marinade and coat thinly with the vegan mayonnaise then press into the walnut mixture to coat.

Arrange on a small baking tray and repeat until all the tofu is coated.

Bake for 20 minutes on one side, then flip and bake for another 20 minutes or so.