Mashed potatoes

Everyone likes mashed potatoes. Put mash on the menu to go with a slow-selling dish, and it whistles out the door. This recipe with its inclusion of boiled onion is particularly fine, and was shown to me by Juliet Peston, for years my co-chef at Frith Street. She in turn got the recipe from her mother, and it almost certainly has its origins in Mittel-European Jewish cooking.

Like so many simple and delicious dishes, there is a certain rigour to the method. The righ