Freeze 1 block Firm Tofu then thaw and press out water after thawed. Then cut into cubes.
Mix together
1 Tbsp Brewers Yeast flakes
1 Tbsp Tamari
1/2 Tsp Onion Powder
1/2 Tsp Garlic Powder
Place Tofu cubes into mixture and gently stir/coat the cubes with the mixture.
Place on sheet pan with parchment paper by separating the cubes for good heat distribution. Don't want them to touch. Then place in a 350 degree oven for 20 minutes then rotate cubes to heat bottom sides and place in oven for 20 more minutes. They should end up being nicely browned and crunchy. Enjoy
Here is a video of Ken demonstrating the process (with Michelle narrating).
Here is Derek Simnett explaining how and why to freeze tofu.