For the chicken: heat a large non-stick frying pan with the light olive oil. Fry the prosciutto slices for 3-4 minutes, or until crisp and golden-brown. Remove and drain on kitchen paper, reserving the oil in the pan.
Season the chicken fillets with salt and drizzle over some olive oil. Return the pan used to cook the prosciutto to the heat and fry the chicken fillets for 2-3 minutes on both sides, or until cooked through. Set aside.
For the dressing: toast the peppercorns in a dry hot frying pan for about a minute until they become aromatic, shaking the pan frequently to prevent the peppercorns from burning.
Roughly crush the peppercorns using a pestle and mortar, then transfer to a mixing bowl.
Add the parmesan, grated garlic and lemon zest to the bowl with the peppercorns, then squeeze in the lemon juice and add the oil. Whisk until well combined, then season to taste with a pinch of sea salt.
For the rustic croutons: heat the olive oil in a large frying pan. Add the herbs and garlic and cook for about 30 seconds, or until aromatic, then add the stale bread cubes and a good pinch of sea salt. Toss well and fry for 1-2 minutes, or until crisp and golden-brown all over. Drain well on kitchen paper.
To serve, place the lettuce leaves into a large mixing bowl. Pour over the roasted peppercorn dressing and toss until all the leaves are well coated. Add the rustic croutons and mix again. Divide among four serving plates, then top each serving with three mini chicken fillets and finish with a couple of slices of crisp prosciutto.