Put the walnuts, chili powder, Bragg liquid aminos, cumin and garlic powder in a blender or food processor and blend until the walnuts are crumb-like (like ground beef)
Heat the olive oil in a large skillet and then add the onion and garlic. Sauté until onions are translucent.
Add the tofu to the skillet and crumble it. Let it cook until most of the water has cooked off and the tofu begins to brown. Add the walnut mixture and continue to cook until warmed through.
Serve in taco shells (see below) and top with your favorite taco toppings such as guacamole, salsa, or pico de gallo