Classic Onion Soup

This onion soup takes an American detour from the French original by using red onions and bourbon instead of the usual yellow onions and white wine. Red onions bring a deeper sweetness when cooked down, and bourbon adds a smoky, caramel warmth that wine can’t replicate.

The flour stirred into the softened onions creates a roux that thickens the broth slightly, giving the soup more body than a thin, brothier version. Once the bourbon goes in, stir until smooth before adding the beef broth. That roux-bourbon base is where all the richness lives.

Toasted French bread on the bottom, Swiss cheese broiled on top until it bubbles and browns. The bread soaks up broth from below and gets sealed by that golden cheese cap. You know the drill, and it never gets old.

Pro Tips

• Saute the red onions low and slow until genuinely soft. Rushing this step leaves them crunchy in the finished soup. You want them silky and almost jammy.
• Let the bourbon cook for a minute after adding it. The raw alcohol flavor needs to burn off before the broth goes in.
• Use oven-safe bowls. Regular ceramic can crack under the broiler, and you don’t want shattered soup.
• Toast the French bread before dropping it in. Untoasted bread dissolves into mush before the cheese even melts.

Variations

• Gruyere upgrade: Swap Swiss for Gruyere for a nuttier, more complex cheese flavor that melts beautifully.
• Thyme and bay leaf: Add fresh thyme sprigs and a bay leaf during the simmer for a more herbaceous, traditional profile.
• Caramelized shallot: Use thinly sliced shallots instead of red onions for a milder, more delicate sweetness.