Easy Onion Sauce

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Close up on a wooden spoon holding onion sauce above a bowl of more sauce

5 from 1 vote

Onion sauce is a British classic that is so easy to make. Packed with flavour from the sweet braised onions, served in a creamy white sauce it is a delicious traditional accompaniment to a roast, and easy way to make it go further. Try my recipe that is just like the one my Grandmother made!

Servings: people

Author: Helen Best-Shaw

Prep Time5

Cook Time10

Ingredients

200 g onions (2 medium) - 1
30 g butter - 2
1 tbsp plain flour (all purpose flour)
200 ml milk - 3
60 ml double cream / heavy cream - 4
white pepper and salt - 5

Metric - USA Cups

Instructions

Prepare the onions Peel and dice the onions into about 1cm / 1/3?pieces.
200 g onions (2 medium)
Sauté the onions Melt the butter in a medium saucepan. Add the onions and stir.
Put the lid on, turn the heat right down and let the onions slowly cook for about 15 minutes, checking and stirring from time to time.
You want the onions to cook, soften and sweeten, but not have too much colour on them. If they start to darken beyond a pale gold the heat is too high. I use a heat diffuser on my gas cooker to further reduce the heat and get rid of any hot spots. Using a heavy saucepan will also help the onions to cook without browning.
30 g butter
Make the roux Once the onions are cooked add the flour, stir it in, and cook for a few minutes.
The flour needs to be properly cooked, or the final sauce will taste floury.
1 tbsp plain flour (all purpose flour), 200 ml milk
Make the sauce Slowly stir in the milk, a little at a time, mixing to a smooth paste each time, before adding more. Going slowly at this stage will stop your sauce forming lumps. which are impossible to get out.
Stir in the rest of the milk, and the cream. Add more liquid if needed for a runnier sauce.
60 ml double cream / heavy cream
Season to taste
white pepper and salt

Notes

Ingredients

Onions - Regular medium sized brown onions.
Butter - Salted / unsalted it does not matter - if using salted add a little less salt when seasoning.
Milk - I used semi skimmed, but it really does not matter that much.
Cream - UK double cream / US heavy cream. The cream is optional but the final onion sauce is richer and creamier if you use it. If you only have a thinner pouring / whipping cream use twice the amount and reduce the milk accordingly.
Seasoning - White pepper is for appearance only, so the sauce does not have flecks of black in it. Both white and black pepper come from the same plant but the pepper berries are processed differently. There is no appreciable difference in flavour in this recipe. If you only have black pepper use it, and grind as finely as you can. There is no need to buy white pepper especially.

Variations

Smooth onion sauce – blitz the finish sauce with a stick blender
Mild onion sauce – put the chopped onion in a sieve and pour over a kettle of boiling water before sautéing them.
Infuse with a few cloves or bay leaf – remove before serving.

Storage & Leftovers

Fridge – Keep your onion sauce in a airtight container or jar for up to 3 days.
Reheating – Bring to a simmer in a small pan over a gentle heat. If needed add some more milk to thin.
Freezer – Freeze in air tight pots, defrost in the fridge before reheating.

Hints and tips

Cook the onions slowly – you want them soft and sweet rather than browned.
When making the roux – flour and butter mixture – cook the flour properly for at least a couple of minutes.
Add the milk to the roux slowly, making sure you have a smooth paste before adding more. After the first few additions you can add a bit faster.

• Please note that the nutrition information provided below is approximate and meant as a guideline only.

• Unless stated otherwise cup conversions have been made with an online tool. For accuracy please check with your favoured conversion tool. We recommend buying inexpensive digital kitchen scales.