Tomato Soup
One pint of canned tomatoes, or 4 large raw ones, cut fine; add 1 quart of boiling water and let boil; add 1 small teaspoon of soda, while foaming add 1 pint of sweet milk, salt, pepper and plenty of butter; when this begins to simmer add 8 small crackers rolled fine.
A cream-of-tomato soup from the era before roux-thickened bisques, thickened with crushed crackers and held together by a pinch of baking soda. The soda is the hinge: it neutralizes enough of the tomato acid that the milk will not curdle when the two meet.
- Soda first, milk secondAdd the soda to the hot tomato and water and let it foam out before the milk goes in. Reverse the order and the acid hits cold protein directly, and the soup breaks into curds that will not come back together.
- Go light on the sodaA scant 1/4 teaspoon is likely enough for this volume. "One small teaspoon" is generous by modern taste and can leave a soapy, faintly metallic flavor.
- Sweet milkSimply fresh unsoured milk, as distinguished from the buttermilk or clabbered milk that older recipes call for by name. Whole milk is the intended thing; half-and-half makes a richer soup.
- CrackersEight small crackers means plain soda crackers or water biscuits, roughly the size of a modern saltine; an ounce or so of crushed saltines is in the right range, and taste before adding the full salt if the crackers are salted.
- The waterA quart of boiling water to a pint of tomato is a thin soup by current standards. Halving the water gives something closer to what most cooks now expect from tomato soup.
- Raw tomatoesIf using the four fresh tomatoes, simmer them 15 to 20 minutes in the water until they collapse, then press through a sieve if you object to skins and seeds. Canned tomatoes need only to come to a boil.
- Heat after the milkOnce the milk is in, keep the pot at a bare simmer and do not let it boil. Even with the soda, a hard boil encourages curdling and scorches the milk solids on the bottom.
- YieldAbout eight cups, serving six as a first course.
Tomato soup thickened with pounded crackers was common in American home cooking in the second half of the nineteenth century, and the baking-soda trick appears in a number of cookbooks of the period as the accepted way to keep the milk from curdling when it meets the tomato. Its popularity tracks the spread of canned tomatoes, which were among the earliest vegetables commercially canned on a large scale in the United States and which made a winter tomato soup possible in ordinary households. Dishes like this one are cheap, made from a pantry can, and stretched with crackers rather than the cream and butter a hotel kitchen would have used. Condensed tomato soup sold in a tin later made the whole procedure unnecessary, which is roughly why the cracker version faded.