Lyon's onion sauce: sweet caramelized onions sharpened with vinegar and white wine in a brown base — French onion soup's saucier cousin.
What you need
Ingredients
Servings
4
Before you start
Mise en place
Yield: About 300 ml
Equipment
Small saucepan
Whisk
Prep checklist
Onion — thinly sliced
3 steps
Method
1
Cook the onions in butter over medium-low with a pinch of salt until genuinely golden, 15 minutes — patience is the recipe.
15 min — timer available in cooking mode
2
Add wine and vinegar; reduce by half, 3–4 minutes.
4 min — timer available in cooking mode
3
Add stock, simmer 8 minutes to sauce consistency, and season. Leave the onions in — they're the point.
8 min — timer available in cooking mode
From the pass
Chef's notes
Taste before serving and adjust salt and acid — the last 30 seconds of seasoning matter more than any single ingredient.
Afterwards
Keep, reheat & pair
Storage
Airtight jar in the fridge, 3–5 days. Press plastic wrap onto the surface of starch-thickened sauces to stop a skin forming.
Freezing
Most sauces freeze 2–3 months; freeze in ice-cube trays for single portions. Emulsified butter/egg sauces don't freeze — they break on thawing.
Reheating
Reheat gently over low heat, whisking; butter- and egg-based sauces split when boiled. Loosen with a spoonful of warm water or stock.
Make ahead
Most sauces keep 3–5 days refrigerated and freeze in ice-cube trays for instant single portions. Emulsified butter sauces are best made within the hour.