Fry the finely chopped onion in the oil until golden. Then add the cleaned pieces of liver with a sprig of rosemary and roast for 2-3 minutes. Deglaze with the wine and reduce a little. Remove the rosemary and liver again and then chop the liver very finely.
Put the liver back into the pan and mix with the chopped anchovies, chopped olives and chopped capers, garlic, diced tomato and the chicken stock. Reduce creamy and season with salt, pepper and lemon juice.
Work in the butter and serve the mixture on toasted bread while it is still warm. Garnish with a little fresh rosemary.