The CWI Cookbook

 1 lemon, yellow part of peel pared & saved, white rind then removed
1/2 pint melted butter

Pare a lemon, and cut it into slices twice as thick as a half-crown piece; divide these into dice, and put them into a quarter of a pint of melted butter.
Obs: Some cooks mince a bit of the lemon-peel (pared very thin), and add it to the above.

From The Cook’s Oracle by William Kitchiner, MD, New York, 1829

Comment: We would rather Dr. Kitchiner had called this “Lemon Butter” but suppose it is a bit late to persuade him to change his mind on the matter. We would also inquire as to the precise thickness of “a half-crown piece” (one of the many places where the English origins of this book show through the good doctor’s attempts to “Americanize” it) but will instead just take a wild guess and suggest making the lemon slices about a quarter inch thick.

Lemon peel can be removed with either a common vegetable paring tool (so long as care is taken not to go so deep as to include the bitter white pith underneath) or with a specialized utensil known as a “zester.” This is something like a single-row grater, with a head containing five or six holes attached to a handle. You scrape the instrument over the fruit as if you were wielding a disposable razor. The zest emerges in thin threads, precisely as needed for this recipe.