Classic sauce soubise is a smooth French onion sauce: a large amount of onion sweated in butter until very soft but not coloured, cooked into a béchamel, then pureed and finished with cream. It takes about 45 minutes and makes about 2 cups, enough for 6 servings. It is served with roast veal, pork, lamb, chicken and eggs.
The sauce should be ivory white and silky, tasting of sweet onion rather than of flour. The secret is patience: the onions are cooked slowly, covered, so they soften and sweeten without browning.
What Sauce Soubise Is
Soubise is a derivative of béchamel, the white mother sauce of French cooking, with onion puree folded through it. An older version thickens the onions with rice instead of béchamel; that version is below too. Because the base is milk and onion, the sauce is mild and slightly sweet, which makes it a gentle partner for pale meats. Add tomato puree and you have sauce Soubise tomatée; add grated cheese to make a quick gratin sauce.
Ingredients
Béchamel
- 2 tablespoons unsalted butter
- 2 tablespoons all-purpose flour
- 1 1/4 cups (300 ml) whole milk, warm
- Pinch of ground nutmeg
Onions and finish
- 3 tablespoons unsalted butter
- 1 1/2 pounds (680 g) yellow or white onions, thinly sliced (about 4 medium)
- 1/4 cup (60 ml) heavy cream
- Salt and white pepper
Instructions
- Sweat the onions. Melt 3 tablespoons butter in a heavy saucepan over low heat. Add the onions and a pinch of salt, cover and cook for 20 to 25 minutes, stirring every 5 minutes, until completely soft and translucent. If they start to colour, add a spoonful of water and lower the heat.
- Make the béchamel. Meanwhile, melt 2 tablespoons butter in a small saucepan, whisk in the flour and cook 2 minutes without browning. Whisk in the warm milk gradually and simmer, stirring, for 5 minutes until thickened. Season with nutmeg.
- Combine. Stir the béchamel into the onions and simmer gently, uncovered, for 10 minutes, stirring so it does not catch.
- Puree. Blend until completely smooth with a stick blender, or in a blender (vent the lid), then press through a fine sieve for the smoothest finish.
- Finish. Return to low heat, stir in the cream and season with salt and white pepper. The sauce should coat a spoon thickly.
Cook and Prep Times
- Prep: 10 minutes
- Cook: 35 to 40 minutes
- Makes about 2 cups (serves 6)
Rice Soubise
For the older style, sweat the same onions in butter, then add 1/3 cup of long-grain white rice and 1 cup of chicken stock. Cover and cook very gently for 30 to 35 minutes, until the rice is completely soft. Puree until smooth, then stir in 1/4 cup cream and 1 tablespoon butter. This version is thicker and works as a side dish as well as a sauce.
Storage
Refrigerate the sauce, covered with plastic wrap pressed on the surface, for up to 3 days. Reheat gently with a splash of milk, whisking until smooth. It does not freeze well; the texture turns grainy.
Frequently Asked Questions
- Can I use red onions? They turn the sauce grey-pink. Use yellow, white or sweet onions.
- Is soubise the same as French onion soup base? No. Onion soup uses deeply browned onions; soubise onions are not browned at all.
- What can I serve it with? Roast veal or pork, lamb chops, roast chicken, poached eggs and steamed vegetables.
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