This is so easy. The cooking time listed reflects 1/2 hour of marination time, but it can be as little as 15 minutes or as long as 24 hours. The recipe doesn't specify which kind of miso, I would assume it's white or yellow miso. This recipe comes from Mark Bittman's Best Recipes in the World. He says "it's a traditional dish, in some parts of Japan the home-cooking equivalent of slathering something with barbecue sauce before cooking. For ease of use and strict authenticity, the miso should be thinned with mirin - it's too thick to use straight. Mark talks about different types of mirin and suggests that hon-mirin is superior to aji-mirin, all good if you have access to a good Asian market!