Heat the griddle to medium. Add oil and diced sweet potatoes, tossing to coat. Squirt water around the potatoes, cover with a basting dome, and steam until softened, adding more water as needed. Once tender, sauté on the griddle until crispy, then move to the side.
Add a little more oil to the griddle and cook the vegetarian beef. Season to taste with Street Taco seasoning.
To build your bowl, layer sweet potatoes, vegetarian beef, black beans, romaine lettuce, pico, guacamole, shredded cheese, and sour cream. Finish with a light dusting of Street Taco seasoning.
