Finely chop eight ounces (225g) of ginger. Add to a pan with 4 cups (approx 1 litre) of water and two cups (400g) of sugar. Bring to a boil and simmer for 45 minutes. Cool and leave to steep overnight. Strain off the liquid, reserving the ginger pieces, into bottles and add a tablespoon of vodka to each to help it keep. This will keep, refrigerated for at least two weeks. The syrup can be used as a mixer for cocktails, or poured over ice-cream or fresh fruit.
Put the reserved ginger pieces into a large, wide-mouthed jar (the ginger should fill the jar to halfway- to two-thirds- full). Pour over enough vodka to fill the jar and fasten the lid. Keep in a dark place for at least a month, shaking occasionally to mix. Strain off the liquid and bottle. Drink chilled as shots or use in cocktails.