Panzanella is a poor, traditional recipe of peasant cuisine, created to recycle ingredients that you have in the pantry; in this Castelli Romani version we do not have the addition of other vegetables as in the Tuscan one, but if you have them you can happily use them.
In the Castelli Romani, the excellent P.G.I. Genzano bread is used, which you can replace with another homemade bread.