[4] The food writer Waverley Root comments that the origins of French onion soup may lie in Alsace, although the dish is popular throughout France and "apparently no region lays particular claim to it".

[6] Although onions were plentiful and affordable by the poor,[1] a medieval recipe in Le Ménagier de Paris, published in 1393, includes among its ingredients ginger and saffron – rare and expensive spices – making this version of the dish one for wealthy households.

[8] According to Alexandre Dumas in his Grand dictionnaire de cuisine (1873), onion soup was introduced to the royal court at Versailles in the 18th century after Louis XV's father-in-law, the exiled Polish King Stanislas, enjoyed it at an inn and insisted on learning the recipe.

[9] A recipe in the Dictionnaire des alimens, vins et liqueurs, published during Louis XV's reign, is similar, but adds "a spoonful of good lean broth" before serving.

[7] According to one writer, the classic gratinée des Halles transcended class distinctions: In Britain, a recipe for French onion soup was printed in The Cook and Housewife's Manual, published in Edinburgh in 1827.

[13] More papers in Britain began giving recipes described as "French onion soup" in the 1880s, but the cooking liquid was either milk or water thickened with flour, and no cheese, crouton or gratinating was specified.