All you need is half a cucumber, some fresh mint (how much depends entirely on your taste, I use a large handful as I'm a fiend for mint in summer), 1 cup of caster sugar, and 1 cup of water.
- Finely chop the mint, and slice the cucumber thinly.
- Put the sugar and water in a large saucepan and heat until they form a clear syrup. Turn the heat down low and throw in the chopped mint.
- Place the cucumber slices in the saucepan and poach for about 20 minutes. Try not to let the slices overlap too much in the pan (you'll probably need to poach them in two batches).
- Fish the cucumber out of the syrup and lay it on a lined baking tray. Put the tray in a low oven, about 90 C (194 F) for and hour and a half to two hours, until mostly dried out (they will remain a bit chewy because of the very high water content of cucumber).
Keep wrapped in baking parchment until needed. The leftover syrup can be kept for use in sweets or cocktails.