Photograph: Dan Jones
Heat the oil in a frying pan, season the duck and stir-fry on high for 1-2 minutes on each side until just cooked. Cool, then thinly slice.
Separate the lettuce leaves and trim the ends off to neaten them. Finely slice the cucumber and spring onion. Fill each lettuce leaf with a little duck, cucumber, spring onion and plum sauce. Finish with a little red chilli.
Get ahead: cook the duck and shred the cucumber, spring onions and chilli a few hours ahead.