Mix beforehand a short pastry dough (pasta frolla) with the ingredients shown above. If it remains too crumbly add a very little water. Make it into a ball, wrap it in greaseproof paper and leave it in the refrigerator for an hour.
Finely chop the onions and brown them in olive oil. Add the tomato paste (diluted with water), celery (finely chopped), olives (stoned and chopped) and caper