Pick the coriander leaves and put them to one side, then add the stalks to a food processor with the lemongrass.
Peel the garlic and ginger, then finely grate into the processor with the lime zest.
Squeeze in the lime juice, trim and add the chilli (deseed if you like), then drizzle in 2 tablespoons of oil, and whiz to a paste.
Rub the paste into the slashes on the chicken, place in a roasting tray, cover, and leave to marinate in the fridge for at least 2 hours, preferably overnight.
When you’re ready, light the barbecue and prepare a hot side and a cooler side.
Place the roasting tray on the edge of the barbie so the chicken starts to cook gently without colouring too much.
When the legs are about half cooked, transfer them directly onto the bars of the barbecue and grill until golden and cooked through, turning regularly – use your instincts, moving the chicken to the cooler side, if needed.
Sprinkle the coriander leaves over, then serve (with a stack of napkins!).