Soak the corn husks in a large bowl of hot water for 30 minutes until they are soft and pliable.
Roast the poblano pepper over a gas flame or under the broiler until the skin is charred, then steam in a covered bowl for 10 minutes before peeling, seeding, and dicing.
In a mixing bowl, whisk together the masa harina and sea salt, then stir in the avocado oil and warm water until a smooth, spreadable dough forms.
In a separate bowl, lightly mash the black beans and mix with the crumbled firm tofu, diced poblano, nutritional yeast, ground cumin, garlic powder, and onion powder.
Lay a corn husk flat on a clean surface and spread about 1.5 tablespoons of the masa dough in the center, leaving a 2-inch border at the bottom and sides.
Spoon a portion of the bean and tofu filling onto the center of the masa dough.
Fold the long sides of the husk inward so the masa completely surrounds the filling, then fold the bottom tail upward to seal.
Place the tamales vertically in a steamer basket with the open ends facing up and steam for 45 minutes until the dough is firm and pulls away easily from the husk.