Heat half of the oil in a large frying pan, add half the pork and cook over a high heat stirring occasionally until brown and crispy. Set aside, heat rest of oil and cook remaining pork in the same way.
In a bowl mil together the ginger, chilli, garlic, spring onions and the coriander. Add the soy sauce, vinegar, fish sauce, sugar and the juice of one of the limes. Mix well.
Pour over the crispy pork and stir to mix together.
Pile the mixture onto the individual lettuce leaves, give each one a squeeze of lime juice or serve with a wedge of lime.