Onion, Thyme and Sour Cream Tart

Real home cooking. You can only get a tart this good if you do it yourself from a home kitchen.  Taking plain old onions and ordinary eggs, this dish magics them into something wonderful.


  1. Make the pastry. By hand: Sift the flour and salt into a large bowl. Cube the butter. Rub it lightly into the flour between your fingertips until it resembles fine breadcrumbs. Finely grate the cheese and stir into the mix with a fork. Add the water gradually, mixing with the fork for a pliable dough that’s neither dry nor sticky (add more flour or water to get it right). Roll the dough lightly into a ball then flatten it into a disk. Wrap in clingfilm and chill for 1 hour. By machine: pulse the flour, salt, cheese and butter until fine. Add the water gradually, pulsing between additions until a dough forms. Stop and test with your fingers to check it’s not too dry. Roll, wrap and chill.
  2. Preheat the oven to 180c. Sit the pastry on a floured board. Grease a 23x3cm loose-based fluted tart/quiche tin. Roll the pastry out in a circle to fit the tin. Without stretching the pastry, roll the pin under it and lift it over and down into the tin. Press into the base and sides for a close fit without it cracking. Use spare pastry to fill any holes/ breaks, leaving a slight overhang on the edges in case it shrinks. Prick the surface lightly with a fork.


  1. Cut a piece of greaseproof paper and lay it into the pastry to protect the base and sides. Fill it with baking beans and bake blind for 10-20 minutes, till the sides are hard and lightly coloured. Remove the paper and beans and brush lightly with egg white. Bake again for 4 minutes. Allow to cool if you have time. Increase the temperature on the oven to 190c.
  2. Meantime, make the filling by thinly slicing the onions. Melt the butter with the oil in a large pan on a low heat. Cook the onions with the garlic and a pinch of salt very slowly for 20-30 minutes until soft and translucent. Remove and allow to cool until needed. Pour off any excess moisture.
  3. Once the onions and base are ready to go, combine and beat the whole eggs, egg yolks, sour cream, double cream, Dijon mustard and seasoning. Grate the cheese over the base and top with the onion mix, then sprinkle with thyme leaves. Carefully pour over the sour cream mix and bake for 30-40 minutes until puffy and golden.
  4. Remove and allow to settle for 10 minutes. Remove from tin.


  1. Sit the tart on a plate or a board. Cut into slices at the table. Serve with various salads and cold meats.


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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