Trim the lemon grass. Peel off the outer layer. Finely chop the stem. Halve the chilli. Finely slice it. Flick out the seeds and white bits for a milder salad. Pop the lemon grass and half the chilli in a bowl with 1 tbsp tamari.
Add the pork to the lemon grass marinade. Stir to mix. Put to one side to marinate while you get everything else ready.
Shred the lettuce into thin strips. Trim and finely slice the spring onions. Pick any large, thick stems out of the watercress. Arrange them all on plates or in bowls.
Pick the leaves off the mint and chervil. Scatter them over the salads with the rest of the sliced chilli.
Scatter half the pack of mixed beans sprouts over the salads. Slice the lemon into wedges.
Warm 1 tbsp olive oil in a frying pan. Lift the pork out of the marinade. Add it to the pan. Stir-fry for 5-6 mins till the pork is golden brown and cooked through.
Arrange the pork over the top of the salads and serve with the lemon wedges for squeezing.