Grate horseradish into the mixture until it reaches the consistency of onion sauce.
Optionally, add a little shallot.
Original Text
Horseradish Sauce.
A tea-spoonful of mustard, one table-spoonful of vinegar, three of thick cream, and a little salt; grate as much horse[201]radish into it as will make it as thick as onion sauce. A little shalot may be added.