Wash the Swiss chard and boil in salted water for about 10 minutes. Drain, squeeze out any excess water and wrap in a cotton kitchen towl to dry. Chop finely. Mince the lardo and mortadella with a knife (or food processor).
In a large bowl, combine the Swiss chard leaves, minced lardo and mortadella, extra virgin olive oil, grated Pecorino, peppercorns and a pinch of salt. Mix well. Prepare the dough by making a well in flour. Add water, oil and a pinch of salt.
Knead well, cover dough in plastic wrap and set aside to rest for at least 30 minutes. Divide the dough into two pieces and roll out with a rolling pin to a thickness of about 1/8 inch. Oil a pie pan.
Drape the first piece of rolled out dough to fit the contours of the pan so that it hangs over the rim. Pour the filling into the pie shell and cover with a second piece of dough, crimping and sealing the edges.
Prick the surface of the with a fork and bake in a preheated 400°F oven for 10 minutes. Lower the heat to 350°F and cook for an additional 20 minutes. Serve warm.