Drain the tofu and slice vertically into 4 slabs. Line a cutting board with a few layers of paper towels or a clean dish towel. Place the tofu slabs on top, wrap the tofu in more paper towels or a clean dish towel, then weigh the tofu down with a heavy cookbook, or a large plate weighed down by a few cans of beans (or use a tofu press). Press the tofu for at least 30 minutes (I usually leave it for an hour), changing the towels in between.
Once pressed, cut the tofu into small cubes (you don’t want large cubes).
In a medium bowl for which you have a lid, whisk together the miso, vinegar, lemon juice, oil, garlic, nutritional yeast, oregano, onion powder, salt, pepper, and red pepper flakes (if using) until the miso paste is dissolved. Add the tofu pieces to the marinade (you can also add the tofu to a large glass jar and pour the marinade on top). Mix well, shaking the bowl or jar, but don’t break up the tofu.
Refrigerate for at least 12 hours, but preferably for 48 hours. The longer, the brinier it’ll taste, like classic feta. It will stay good in the fridge for up to 7 days.