For the pastry, dissolve yeast and sugar in the water and let stand for 10 minutes until it begins to foam.
Mix the oil, egg and salt and flour and knead into a pliable dough. Form a ball with the dough and roll it round in a large, greased bowl. Cover with a cloth and leave in a warm place for 45 minutes to 1 hour.
In the meantime, cut the onions into very thin rings. Heat 3 tablespoons of olive oil in a heavy medium-sized saucepan. Fry the onions for 10 to 12 minutes until soft.
Add the tomatoes, pepper and garlic and mix well. Add the saffron, anise seed, salt and pepper and cook without a lid for 30 minutes, stirring occasionally. At the end of the cooking time, there should be no more liquid.
Preheat oven to 200 C / Gas 6.
Roll the pastry out on a floured work surface into a circle about 30cm across and line the bottom and sides of a 25cm springform tin with it. If the pastry does not quite fit, take care to ensure that everything is covered well. Roll the edges of the pastry inwards.
Spread the cooled filling evenly on the pastry and smooth out the surface. Place the olive halves on top and put it in the preheated oven for 35 minutes. After baking, brush the pastry with olive oil. Serve fresh, hot or warm.