Wash, dry and halve the kidneys, cut out the white sinew and slice. Rub the kidneys with salt and leave them to stand for 30 minutes. Wash the kidneys in lukewarm water and pat them dry. Finely dice the onion and garlic.

Heat the oil in a frying pan and fry the onion and garlic until transparent. Season the kidneys with pepper, dip in flour, shake off any excess and fry the kidneys for 5 minutes, turning frequently.

Pour the Cognac over the kidneys, flame and leave to burn out.

Season the cream with salt and stir it into the kidneys. Stir the butter, sugar and mustard into the sauce and heat for 8 minutes, without allowing the sauce to boil.

Serve with: braised courgettes, French bread and Waldorf salad.