Cut Tofu: Drain the tofu and pat dry with paper towels for easier handling. Cut the tofu into 1/2" cubes.
Dry & Press Tofu: Put the tofu cubes between layers of folded paper towels (at least 4 layers on top and under tofu). Then put a heavy pan (or something similar) on top of the tofu to press it for at least 5 minutes.
Heat Pan & Coat Tofu: Generously coat the bottom of a large pan with oil and put it over medium/high heat (see note 2). Pat down the tofu one last time with a paper towel. Put the tofu and cornstarch in a Ziploc baggie. Seal the baggie and gently shake to coat the tofu (see note 3).
Fry Tofu: Put the tofu in the hot oil. It should sizzle right away. Don't overcrowd the pan. Fry in batches if needed. Fry for about 4-6 minutes or until slightly golden brown while flipping the cubes every couple minutes with a spatula to ensure all sides become crispy. Remove the tofu from the pan and place on paper towels to remove excess oil. Use in tacos immediately.
For the Tacos:
Make Sauce: Stir together all sauce ingredients until well combined. Set aside.
Make Salsa: In a medium/large bowl, combine the black beans, corn, bell pepper, jalapeño, salt and lime juice (optional). Set aside.
Assemble: Put crispy tofu cubes, the sauce, a spoonful or two of salsa and a couple slices of avocado in a tortilla. Serve with lime wedges and a sprinkle of cilantro (optional). Enjoy!
Notes
Note 1: Use oil with a high smoke point such as vegetable oil, canola oil or coconut oil. Note 2: It is important to heat the oil before coating the tofu because you want to fry the tofu immediately after you coat it with the cornstarch. Note 3: If you do not have a baggie, put the tofu and cornstarch in a bowl and gently toss with your hands to coat.