Cut the chicken livers as needed and mix them with 1 tablespoon of mustard and half of the lemon juice. Leave in the fridge to marinate for 1 hour.
Then boil them in a water bath or saute in a little oil and water for about 10 minutes. Season with salt and pepper. Mix the remaining 1 teaspoon of mustard with the cream and lemon juice.
Season with salt and black pepper and serve the livers with the sauce. Serve the chicken livers with lemon with a garnish of vegetables.