Heat a dash of olive oil in a frying pan over low heat. Add the onion and let it soften in ten minutes (do not fry them brown). Add the anchovies and let it melt. Add the chicken liver and capers and heat until the livers are cooked. Deglaze with a dash of vin santo and light it to allow the alcohol to evaporate. Transfer the whole to a high bowl and puree with the blender or in the small bowl of the food processor and puree the whole.