Mustard Sandwich
Cream two tablespoonfuls of butter with one tablespoonful of prepared mustard. Spread a thin layer between thinly cut slices of rye bread. Garnish with a pickle.
A two-ingredient compound butter on rye. The only thing that can go wrong is proportion, and the original ratio is stronger than it looks.
- Prepared mustardIn period usage this meant a ready-mixed, vinegar-based mild yellow or brown table mustard, not Dijon and not English mustard made up from powder. A tablespoon of Colman's or a hot Chinese mustard against two of butter would be close to inedible; use a mild American or German-style prepared mustard, or cut the quantity by half if you are working with something sharp.
- Butter temperatureThe butter has to be genuinely soft, left at room temperature until it creams easily, or the mustard will bead out rather than emulsify into it. Cream the butter smooth first, then beat the mustard in a little at a time.
- RatioTwo parts butter to one part mustard is assertive. It is meant to be spread in a thin layer, as the recipe says; treated like ordinary sandwich butter it will overwhelm the bread.
- The ryeA close-grained, lightly soured loaf, often with caraway, suits this. A deli rye or a light pumpernickel is the right register; a very dark, dense German rye will fight the mustard.
- YieldAbout 3 tablespoons of mustard butter, enough for a few rounds of sandwiches cut in halves. It keeps several days covered in the refrigerator and is worth making in quantity for cold beef or ham.
Compound butters were a mainstay of the American sandwich book at the turn of the last century, when a "sandwich" was often a tea-table or lunch-basket item rather than a full meal. Books of this kind ran to many short entries, a good number of them variations on the same idea: cream something into butter, spread it thin, cut the bread thinner. Classified and named beurres composés were a fixture of professional French cookery, and in domestic American use the same trick produced a range of distinct sandwiches from a single pound of butter and whatever was in the pantry. A pickle garnish is a common period finish for plain savoury sandwiches, appearing beside cold meat, cheese and egg sandwiches, and filled out the plate as much as it seasoned.