Brown Sauce

Ingredients

• 1 onion
• 75 g butter
• 1 dl flour
• 1 l bouillon
• black pepper

Method

Dice the onion into 5 mm pieces. Heat 50 g of the butter in a heavy-based pan over medium heat until foaming, then add the onion. Cook for 8–10 minutes, stirring occasionally, until the edges caramelize to deep gold. The onion will sweeten as its sugars browning|caramelize — this is your flavour foundation. Tip into a bowl and set aside.

Return the pan to medium heat with the remaining 25 g butter. Once melted, add the flour in one go and stir constantly with a wooden spoon or whisk. The mixture will tighten first, then begin to loosen as the flour toasts. Continue for 8–12 minutes until the roux deepens from pale straw to chestnut brown. You're after the colour of old mahogany; stop before it turns the shade of dark chocolate or it will taste burnt. The darker the roux, the less thickening power it retains — this is a trade-off: deeper colour and flavour at the cost of viscosity.

Add the bouillon cold, not hot. This matters. Cold liquid hitting hot roux creates a violent emulsion that incorporates the starch evenly and prevents lumps. Pour in roughly 200 ml at first, whisking hard. The mixture will seize and thicken; keep whisking until smooth, then add the remaining bouillon in three batches, whisking between each addition. Once all is incorporated, bring to a simmer over medium heat.

Simmer for 8–10 minutes, stirring frequently. The sauce will thicken as the starch gelatinizes and the fat from the roux emulsifies into the liquid — you're watching for a coating consistency that clings lightly to the back of a spoon. Fold in the reserved caramelized onion and several grinds of black pepper. Taste and adjust seasoning.

If using meat, add it now or serve the sauce separately as a condiment. Brown sauce is a classical-sauces|classical sauce foundation: use it under roasted game, beef, or offal. It holds for two days refrigerated, and freezes well.