Cut the tofu into 1-inch cubes (or smaller, 1/2-inch cubes if you prefer).
In a mixing bowl, whisk together the miso, lemon juice, and vinegar; you'll have a thick, smooth paste. Add the water and whisk till smooth, then whisk in the garlic, nutritional yeast, salt, pepper, and oregano.
Place the cubed tofu in an airtight container (preferably one that's wide enough to allow tofu to rest in a single or double layer) and pour the marinade over the tofu. Shake to distribute the marinade over the tofu, then cover the container and transfer it to the fridge for at least 4 hours, but preferably overnight. The tofu will become more flavorful as it marinates. Serve with salad, pasta, in a grain bowl, or however you’d normally enjoy feta cheese!