52 THE BOOK OF RARER VEGETABLES 
longer than three years, as the root growth after that 
time does not thicken, but divides and gets harder and 
less valuable. 
To Make Horse Radish Sauce 
Simmer a small teacupful of finely rasped Horse Radish 
in half a pint of broth. Then thicken, by adding the 
yolks of two eggs beaten up with a dessert-spoonful of 
tarragon vinegar. Add a little pepper and salt and 
serve. To make cold Horse Radish sauce, add to a small 
teacupful of gratings, half a pint of mayonnaise. Serve 
as cold as possible. 
