Heat the olive oil in a medium sized saucepan.
Add the pancetta and fry for 2 minutes, until just turning golden. Add the shallots and fry for a further 2 minutes.
Add the wine, turn up the heat and leave to bubble away for 3 minutes to reduce slightly. Add the stock and peas, then bring to the boil and simmer for a further 3 minutes.
Set aside until ready to serve. Just before serving, place the pan over the heat and bring to the boil, add the halved heads of lettuce and simmer for 1-2 minutes or until the lettuce has just wilted.
Season to taste, sprinkle with mint and serve immediately.