Step 1

Melt the butter in a wide-bottomed saucepan. Add the chicken breasts, skin side down.

Step 2

Cook gently without browning on both sides for about 5 minutes in total.

Step 3

Sprinkle in the flour. Mix well before adding the lemon zest and juice and tarragon, followed by the chicken stock.

Step 4

Cover the saucepan and place over a very gentle heat for 20 minutes so that the sauce barely bubbles.

Step 5

Check the chicken breasts are cooked – they should be very firm to the touch and the juices should run clear if a skewer is inserted.

Step 6

Stir in the crème fraîche or sour cream, and season to taste with salt and pepper.