Onion Sauce

Onion Sauce

This is a basic Onion Sauce recipe that can be used in a variety of dishes including Fish Pie.

  • Servings : 2-4
  • Prep Time : 1m
  • Cook Time : 10m
  • Ready In : 11m


  • 2 oz plain flour
  • 1/2 pint of semi-skimmed or full cream milk
  • 1 oz butter
  • 1 large onion or 2 medium onions
  • Pinch of salt & pepper


Step 1

Measure out the flour, milk and butter separately in preparation.

Step 2

Finely chop the onion or onions.

Step 3

Using a medium sized saucepan, boil enough water to cover the onions, add the chopped onion, bring to the boil and then simmer for 8-10 minutes.The onion should be just cooked.

Step 4

In a 2nd large saucepan on a low heat, pour milk and add all the flour, whisking as introduced until they are thoroughly mixed together. Gently heat the mixture.

Step 5

When the milk is warmed and starts to thicken with signs of bubbles, add all the butter. Continue stirring with a spoon (don’t whisk) until the butter has melted completely.

Step 6

Add a pinch of salt and pepper and stir in.

Step 7

Remove the onion from your other saucepan, straining most of the water and add it to the sauce mix in your 2nd pan.

Step 8

Continue to heat over a low heat and stir gently. You can add some of the onion water if more liquid is needed.The consistency should be that of a smooth paste that pours.

Step 9

Remove from the heat and serve. Hints and tips; If the white sauce should become too thin add a little cornflour mixed with milk not flour and water. This will turn the mixture lumpy.

Top Tips

Don’t let the sauce boil or overheat in the saucepan. If it does, remove what you can from the pan and continue, being careful not to scrape any burnt bits from the bottom as these will taint the flavour!

Recommended Equipment

  • Large stainless steel saucepan
  • Metal whisk
  • Wooden spoon
  • Digital kitchen scales for measuring