Soak the baccala` for 12 hours in fresh water to remove the salt. Change the water 2-3 times.
Soften the raisins by bathing them in lukewarm water.
Lightly coat with flour the baccala` fillets.
Put some oil in a large saute` pan and give a quick coating on all sides of the fillets.
In a separate saute` pan, saute` the onion.
Add the sauted onion to the baccala`.
Toast very lightly the pine nuts and the fennel seeds. The toasting is necessary to extract their oils and enhance their flavors.
Add to the baccala` the tomatoes, the pine nuts, the fennel seeds, the raisins and the peperoncino.
Continue cooking the baccala` and if it gets a bit dry, add some hot water. At the end the sauce should be dense. Pay special attention in turnig the fillets as they become fragile and can break up.
Add salt as needed, but be careful that the baccala` could still have some residual salt of its own.
Sprinkle fresh pepper and the baccala` is ready to be served.