This sauce is not only flavourful, but also very practical given that it can be prepared in advance and frozen. Moreover, it can easily be doubled or even tripled. Combine a variety of vegetables, including rehydrated dried mushrooms, which provide a lot of flavour, carrots, celery and onions, tomato paste for creaminess, and miso and soy sauce, which concentrate the flavours. Let simmer and then serve this delicious vegetarian sauce over pasta.