Preheat oven to 350 degrees.
Lay pancetta slices on parchment paper lined sheet tray. Bake until golden and crispy. When finished, allow to cool and drain on a cooling rack or paper towels.
Cut peaches in half and remove the pit. Generously cover the cut sides with extra virgin olive oil and sprinkle with salt. Grill peaches on a very hot grill, cut side down, until grill marks are achieved. This should take about one and a half minutes. Set peaches aside and allow to cool to room temperature.
Thinly slice the spring onions and mix with mustard greens.
In a mixing bowl, lightly dress your mustard greens and spring onions with a drizzle of olive oil, squeeze of lemon, and pinch of salt.
Slice peach halves into 4 or 5 pieces.
Divide ingredients equally onto 4 plates and drizzle with balsamic vinegar.