How to Make It
In a medium bowl, beat the eggs with the water and salt. Beat in the mint, parsley, chives, oregano and thyme.
In a 10-inch nonstick skillet, melt the butter. Add the eggs and cook over moderately low heat, without stirring, until just beginning to set at the edge, about 3 minutes. Using a spatula, lift the edge and tilt the pan so the egg mixture can seep underneath. Continue to cook, lifting the frittata and tilting the pan occasionally, until the frittata is just set and creamy on top, 3 to 5 minutes longer. Scatter the prosciutto over the frittata and slide it onto a plate. Garnish with coarsely ground pepper and shaved Parmigiano and serve right away.