Radicchio, Fennel, and Olive Panzanella

6 ounces country-style bread, torn into bite-size pieces (about 4 cups) 1 tablespoon finely grated lemon zest 1/2 cup olive oil, divided Kosher salt, freshly ground pepper 1 small shallot, finely chopped 2 tablespoons fresh lemon juice 2 tablespoons red wine vinegar 1 tablespoon chopped fresh oregano 1 small head radicchio, torn into bite-size pieces 1 small fennel bulb, thinly sliced 1 cup fresh flat-leaf parsley leaves with tender stems 1/2 cup green olives, pitted, halved 3 ounces aged sheep's-milk cheese (such as Manchego), shaved 3 ounces hard salami, thinly sliced