I'm slightly confused by the rice wine vinegar. I thought there was rice wine (shaoxing), and rice vinegar. Which should I use?
Nigella's Mirin Glazed Salmon (from Nigella Express and on the Nigella website) is pan fried salmon coated with a sauce made from mirin, brown sugar, rice wine vinegar and soy sauce. The sauce is made in the frying pan that the salmon is cooked in so it is very quick and easy.
There is no difference between rice wine vinegar and rice vinegar, beyond the name used on the bottle. To make vinegar you need alcohol present to ferment into the acetic acid that gives the vinegar its sharpness. So rice vinegar is made from rice that is fermented into rice wine and then on into vinegar. This is the same as taking young rice wine and fermenting it into the vinegar. Rice wine itself (shaoxing) is often aged before it is drunk or used, so has a much darker colour. However we would mention that there are two types of rice/rice wine vinegar - unseasoned and seasoned (usually labelled as "seasoned" and sometimes called sushi vinegar). Nigella uses the unseasoned type. Seasoned vinegar has added sugar and salt and is not suitable for this recipe.