Why do so many recipes state the amount of fresh ginger in “thumbs” or centimetres. With it being so variable in shape, why don’t you use weight?

Nick, by email

Let’s gather some of the Guardian food troops and ask them to explain themselves. First up in front of the class is our own perfectionist, Felicity Cloake : “That’s a very good question, and I don’t think there is a very good answer,” she says. “Maybe it’s just convention, because sometimes it feels a bit fussy to give a precise weight for the likes of ginger, onions and other staples if you’re not, say, Heston Blumenthal.” Often, it doesn’t really matter that much, either: “If you give a precise weight, people will perhaps think it’s very important and worry if they’re a few grams out,” she adds.…