In a large bowl, mix the cornstarch, salt, pepper, and 5 spice powder.
Coat the tofu in batches. You can add around 1/3 of the tofu cubes (depending on the size of your pan/wok) into the cornstarch mix. Roll the tofu into the starch until they’re white and well coated well.
Check the heat of the oil. If you see small bubbles, you can test it out by getting a small piece of tofu. Add it in the oil and if it immediately sizzles very rapidly, it’s good to do! Remember, you’ll want to fry the tofu quickly to get them crisp evenly so the oil has t be very hot.
Add in the first batch of coated tofu. Make sure not to overcrowd the pieces of tofu so they can all cook well.
Leave the tofu to cook for 4 to 5 minutes, flipping halfway through as needed, until all sides are cooked through and crisp. You’ll know the cornstarch s cooked through when it dries up and gets firm and crisp. The tofu won’t turn to a golden brown—just a very pale yellow.
While the first batch of tofu cooks, you can go ahead and add in another batch of tofu cubes into the starch mixture to coat it well.
When the first batch is done cooking, remove the tofu cubes from the oil. Transfer it to a strainer or cooling rack to cool. Don’t place them on a plate with paper towels since they’ll get soggy. Do not cover them as well.
Add in the next batch of tofu cubes into the oil. Repeat the coating and frying process for the rest of the tofu—so you’ll repeat this 3 to 4 times depending on the size of your pan/wok.
Set aside the fried tofu cubes while we sauté the rest of the ingredients. Be sure not to cover the tofu to prevent them from sogging.
Remove the oil form the wok/pan.