Peel and very finely slice the ginger lengthways: a mandolin or truffle slicer is best. Cut the lemon grass in half lengthways. Slice the lemons in half, trim a length of zest from around each lemon half and juice the remainder. Gently tie each piece of zest in a knot.
In heatproof glasses divide the ginger, lemon grass, lemon juice, zest and honey. Top with boiling water, mix and leave to steep for five minutes. Add optional shots of whisky if wished.