Instructions

Ask your butcher to mince the meat finely, or chop it yourself with a knife for a better result.
Finely slice the onion and chop the gherkins and capers.
In a bowl, mix the meat with the mustard, oil, salt and pepper.
Add the onions, gherkins and capers, then mix quickly without overworking the meat.
Shape four small mounds on the slices of bread, make a well in the centre of each and place an egg yolk in it.
Serve immediately, the meat must stay very fresh.

Light version. Replace half the meat with very lean beef and add a little chopped parsley.

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