Onion Sandwich
Slice a mild sweet onion and lay in salted ice water for a half-hour. Mix with a good mayonnaise dressing, and place slices of onion between well buttered slices of Boston brown bread cut thin.
A three-ingredient sandwich that lives or dies on the onion and the bread. The ice-water soak is the whole technique, not an optional refinement.
- The soak is the hingeThirty minutes in salted ice water draws out the sulfur compounds that make raw onion harsh and lingering. Drain well and pat the slices dry, or the mayonnaise will thin and slide out of the sandwich.
- Which onion"Mild sweet onion" in this period would most likely have meant a Bermuda; today Vidalia, Walla Walla, Texas 1015 or a plain sweet yellow onion all work. A sharp storage onion will overwhelm the brown bread even after soaking.
- Slice thicknessAim for about 1/8 inch on a mandoline or a very sharp knife. Thick rings slip out when the sandwich is bitten; shaved paper-thin, they disappear into the dressing.
- Boston brown breadA steamed loaf of rye, cornmeal and wheat sweetened with molasses, traditionally cooked in a cylindrical mold or can, so slices come out round. Canned brown bread is still sold in New England; a dark pumpernickel or dense rye is the closest substitute. Chill the loaf before slicing thin.
- Butter both faces"Well buttered" is functional here. The butter waterproofs the crumb against the wet onion and the dressing, which matters in a bread this soft and moist.
- Mayonnaise and raw eggPeriod mayonnaise was made fresh from raw yolks and nothing in this sandwich cooks the egg. Use commercial mayonnaise or pasteurized eggs, particularly if serving anyone pregnant, elderly or immunocompromised.
- Yield and servingThe recipe gives no quantities; one medium onion and a brown bread loaf will make a plateful of small tea sandwiches. Assemble within an hour of serving; trim crusts if the loaf has them and cut in halves or quarters.
The onion sandwich was a fixture of American tea tables and card parties in the first decades of the twentieth century, when the sandwich book was its own publishing genre and hostesses were expected to produce a dozen fillings from a pantry. Pairing it with Boston brown bread marks the recipe as regional New England: that steamed loaf of rye, cornmeal and molasses was a Saturday-night companion to baked beans, and it was pressed into service for tea sandwiches, where its sweetness and dark color set off pale, sharp fillings. The salted ice-water soak for raw onion is older than the sandwich itself and turns up in earlier cookery for salads and relishes, a cook's answer to onion pungency long before anyone could name the sulfur compounds responsible.