Potato, Onion & Herb Soup


  1. Peel the potatoes. Sit them on a board and chop into very small even sized pieces.
  2. This helps speed the cooking process and allows the butter to infuse the vegetables.
  3. Dice the onion finely. Crush the garlic. Chop the tarragon or other fresh herb.
  4. Get your stock from the fridge or make it up using a Knorr stock pot or Low Salt Marigold Bouillon using the amount of water specified on the packet.
  5. If making croutons: Cut crusts off bread. Dice each slice into small cubes.


  1. Melt the butter in a heavy based saucepan on medium heat. Add the onion, garlic and a
  2. few grains of salt to reduce the risk of the onion burning. Don’t add too much. Stir with a wooden spoon on lower heat for 1 minute.
  3. Add the potato pieces. Stir well to coat in the butter.
  4. Sweat the vegetables; lay a piece of greaseproof or silicone paper or a butter wrapper (inside downwards) over them to seal the flavours in and soften them. Reduce the heat so they don’t catch and burn. It’s worth checking and stirring a couple of times as they cook if they need it.
  5. Leave them to sweat for 10 minutes – without browning at all. Remove the paper once the vegetables are cooked through and soft.
  6. Add the stock. Bring the mix to a boil over an increased heat. Reduce it once more. Put the lid on the pan and let it simmer and bubble very gently for 10 minutes. Meantime, fry the diced bread in a little oil and butter, turning until just crisp. Turn frequently for 2-3 minutes or so.
  7. Remove soup from the heat. Add the tarragon. Blitz everything with a hand blender until smooth.
  8. Stir the milk in. Taste and add salt and pepper or a little lemon juice if you need to.


  1. Pour into bowls. Sprinkle with optional croutons. Serve with buttered muffins. Or Welsh Rarebit. Or enjoy it with warm crusty bread and butter. It keeps for 2 days and re-heats well.

Useful Cooking Information


Metric Imperial
10 g½ oz
20 g¾ oz
25 g1 oz
50 g2 oz
75 g3 oz
110 g4 oz
150 g5 oz
175 g6 oz
200 g7 oz
225 g8 oz
250 g9 oz
275 g10 oz
350 g12 oz
450 g1 lb
500 g (½ kg)18 oz
700 g1½ lb
900 g2 lb
1 kg2¼ lb
1.3 kg3 lb
1.8 kg4 lb
2.2 kg5 lb


Metric Imperial
50 ml2 fl oz
75 ml3 fl oz
100 ml3½ fl oz
125 ml4 fl oz
150 ml5 fl oz¼ pint
200 ml7 fl oz
250 ml9 fl oz
300 ml10 fl oz½ pint
425 ml15 fl oz¾ pint
600 ml20 fl oz1 pint
800 ml1½ pint
1 l1¾ pints
1.2 l2 pints
1.5 l2½ pints
1.8 l3 pints
2 l3½ pints


Metric Imperial
5 mm¼ inch
1 cm½ inch
2 cm¾ inch
2.5 cm1 inch
3 cm1¼ inches
4 cm1½ inches
5 cm2 inches
10 cm3 inches
15 cm4 inches
20.5 cm6 inches
23 cm9 inches
25 cm10 inches
30 cm12 inches

Spoon measures - mean level measures unless the recipe says 'heaped'

Eggs - are always large for baking, unless recipe says otherwise

Oven Temperatures

Gas °F °C
Mark 1275140

Fan assisted ovens - remember to reduce temperatures by 20°C

Most Useful US/European Conversions

ButterUS 1 cup / 2 sticks8 oz220 g
SugarUS 1 cup6 oz175 g
FlourUS 1 cup4 oz110 g
LiquidUS 1 cup8 fl oz225 ml
Prepped OnionsUS 1 cup4 oz110 g
Cheese, GratedUS 1 cup4 oz110 g
Diced FruitUS 1 cup5 oz150 g
Fresh BreadcrumbsUS 1 cup2 oz55 g

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