No need to peel the ginger, just scrub the skin clean with a vegetable brush and grate or chop finely in a chopper.
If you have a pestle and mortar, lightly crush the lavender buds to release their essential oils and aroma. If you don't, making sure that your hands are clean, lightly crush the buds between your fingers or in your hands.
Place everything into a small pan and bring to a boil.
Simmer for 10 minutes on the lowest heat to allow the flavours to develop and the syrup to thicken.
Strain and discard the ginger pulp.
Cool to room temperature, cover and leave somewhere cool until needed. No need to place in the fridge.
The Lavender, Lemongrass and Ginger Spritzer
Rinse the lemongrass stalks and bruise them. That means, using the back of a big knife, pound down on the base (the thick part) of the lemongrass, to release the flavour, aroma and essential oils.
Divide the ginger and lavender syrup amongst 4 glasses.
Place 3-4 ice cubes in each glass.
Top up with the sparkling water.
Place a lemongrass stalk in each glass, stir to infuse, then serve immediately.
Notes
Total time doesn't include cooling down of the syrup. If your syrup is still warm when you make this drink, compensate by adding more ice cubes.