Best Spices for French Onion Soup

French onion soup gets most of its flavor from technique: onions cooked slowly until deeply browned, then simmered in stock and finished under a cap of bread and melted cheese. The seasoning is spare. All three recipes cited here use thyme, a bay leaf and black pepper, and each adds some wine. This page covers what each seasoning does, how the recipes differ, and when to add each one. Quantities appear only where a named recipe gives them.

At a glance

Seasoning	Job in the pot	In the recipes cited
Thyme	Savory, sharp herbal note against the sweet onions	All three¹²³
Bay leaf	Subtle herbal background	All three¹²³
Black pepper	Gentle pungency	All three¹²³
Parsley	Green note, often with thyme and bay as a bundle	Saveur¹
Nutmeg	A faint warm note	Bernard Laurance³
Wine or sherry	Acidity, depth	All three, in different forms¹²³
Gruyère	Nutty, savory topping	All three¹²³

The onions do most of the work

Every recipe here starts with a long, slow cook of the onions. Saveur’s version, based on Patricia Wells’s Bistro Cooking, cooks thinly sliced yellow onions in butter for 40 to 45 minutes until they just begin to brown, then about an hour more until caramelized.¹ The America’s Test Kitchen recipe published by PBS SoCal cooks about 4 pounds of yellow onions covered for an hour, then 1½ to 1¾ hours longer until very soft and golden brown.² Bernard Laurance gives no time and says only that the onions should color without burning.³ Two of the three add a little sugar to the onions.¹³

Forty minutes is the low end of these recipes; the ATK method runs past 2½ hours.

The seasonings and what each does

Thyme: the savory counterweight

Thyme appears in all three recipes: six sprigs in Saveur’s and in ATK’s (tied with twine), unmeasured in Laurance’s.¹²³ It is not the only herb in every version: Saveur adds six sprigs of parsley, and all three add bay.¹²³ The characteristic constituents of thyme oil are thymol and carvacrol,⁴ which give the herb the sharp, savory edge that cuts the onions’ sweetness (that last effect is our kitchen judgment). America’s Test Kitchen classes thyme as a hearty herb whose volatile flavor compounds are somewhat more heat-stable, so it can go in early and simmer.⁵ Fresh sprigs are easy to fish out; for dried, see fresh thyme vs. dried.

Bay leaf: background depth

Each recipe uses bay: two fresh leaves in Saveur’s, one in ATK’s, unmeasured in Laurance’s, who offers a bouquet garni as an alternative to thyme and bay.¹²³ Britannica gives the classic bouquet garni as sprigs of parsley and thyme and a bay leaf, removed before the dish is served;⁶ Saveur’s herb list matches it exactly.¹ Atlas Obscura describes bay’s flavor as herbal, bitter and slightly piney,⁷ and J. Kenji López-Alt says bay brings out the meaty flavors of beef and chicken.⁸ Take the leaf out before serving; López-Alt compares eating one to eating a fish bone.⁸ See bouquet garni and cooking with bay leaves.

Black pepper: the finishing spice

All three recipes season with black pepper, to taste.¹²³ Its flavor comes principally from piperine.⁹ For grind size, see cracked vs. ground black pepper. Black pepper is not the only spice in every version: Laurance also adds a little nutmeg.³

Nutmeg: an optional warm note

Laurance seasons his soup lightly with salt, “a little pepper and nutmeg.”³ Neither of the other two recipes uses it. In our judgment a few gratings is plenty; see cooking with nutmeg, and if it takes over, too much nutmeg.

Wine: which kind?

The recipes do not agree, so here they are side by side:

Recipe	Wine
Saveur (after Patricia Wells)¹	1 cup white wine plus ½ cup and 3 tbsp sherry
America’s Test Kitchen, via PBS SoCal²	½ cup dry sherry
Bernard Laurance³	10 cl (about ⅓ cup) dry white wine

None of the three uses red wine, port or vermouth; white wine, dry sherry or both is the common thread in the recipes checked.

Stock: beef, chicken, or water

Recipe	Liquid
Saveur¹	2 quarts beef stock
America’s Test Kitchen, via PBS SoCal²	4 cups low-sodium chicken broth, 2 cups beef broth, 2 cups water plus extra for deglazing
Bernard Laurance³	2 L water with one Maggi stock cube

In our judgment beef stock gives the deepest flavor, but ATK’s mix of chicken and beef broth and Laurance’s water-and-cube version both appear in tested recipes. With store-bought broth or a cube, add salt late and taste first (our advice).

Gruyère and the topping

All three recipes top the soup with Gruyère: 8 ounces for ATK, 200 g for Laurance (“the cheese matters!!”), and 6 cups in Saveur’s version, which also adds 2 cups of Parmigiano-Reggiano and lists two smashed garlic cloves alongside the baguette.¹²³

When to add each seasoning

From the recipes above:

Sugar (optional): with the onions.¹³
Thyme, bay (or a bouquet garni): with the stock, then simmered; Laurance adds them with the cube and sugar.³
Wine or sherry: after the onions have browned and before or with the stock; the exact order varies by recipe, so this is our method.
Salt, pepper, nutmeg: to taste near the end, especially with salty broth.³
Remove the bay leaf and thyme stems before ladling into bowls.⁸⁶

French Onion Soup, Saveur, 2007 (based on Patricia Wells, Bistro Cooking). saveur.com · Publication ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷
Winter Recipe: French Onion Soup, Katherine Spiers, PBS SoCal, 2013 (America’s Test Kitchen recipe). pbssocal.org · Publication ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³
Onion Soup Gratin, Bernard Laurance, La Cuisine de Bernard, 2012. lacuisinedebernard.com · Publication ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰
Thymus vulgaris (PROSEA), S.H. Widodo, via Pl@ntUse. uses.plantnet-project.org · Reference work ↩
Our Guide to Fresh Herbs, Liz Bomze, America’s Test Kitchen, 2019. americastestkitchen.com · Publication ↩
Bouquet garni, Encyclopaedia Britannica. britannica.com · Reference work ↩ ↩²
What Is a Bay Leaf, Exactly?, Andrew Coletti, Atlas Obscura, 2023. atlasobscura.com · Publication ↩
Bay leaves are an optional ingredient, David Leite with J. Kenji López-Alt, The Splendid Table, 2014. splendidtable.org · Publication ↩ ↩² ↩³
Black pepper, Encyclopaedia Britannica. britannica.com · Reference work ↩

The Best Seasonings for French Onion Soup: Thyme, Bay, Pepper and What Else Goes In