Fill saucepan with water and bring to vigorous boil over high heat. Add tofu and cook for 2 minutes. With slotted spoon, remove tofu to colander. When cool enough to handle, squeeze out some moisture. It is fine to mash up tofu a bit while doing so. Place tofu in food processor or blender and process until smooth. Scrape down sides of bowl, add miso, mix until smooth. Season with salt and mirin and pulse again until creamy. Scrape down sides of bowl as necessary. Transfer to glass jar, cover with tight-fitting lid, and store in refrigerator for up to 3 days.
