3 parsnips, 1 onion, 1 head of celery, 1/2 oz. of butter, 1/2 pint of milk, 1 quart of water, 1 tablespoonful of Allinson fine wheatmeal, 1 tablespoonful of vinegar, pepper and salt. Scrape the parsnips and cut them up finely, cut up the celery and onion, and set the vegetables over the fire with the water, butter, and pepper and salt to taste: when they are quite tender rub them through a sieve. Return the SOUP to the Saucepan, add the milk and the thickening, boil up for five minutes, and before serving add the vinegar. This latter may be left out if preferred.
The Allinson Vegetarian Cookery Book, by Thomas R. Allinson (Year 1915)