I never cook the mint sauce. same ingredients but just put in a jar chopped up covered in vinegar/sugar mix . Tastes very fresh even after months!
I also tried
http://www.channel4.com/4food/recipes/tv-show/come-dine-with-me-recipes/series-9/mint-and-mascarpone-ice-cream-recipethe kids don't like it as it has mint bits in it instead of chocolate and it tastes not like the one from the icecream parlour but it think it is rather nice - all the more for me
found on allotments 4all forum:
mint cordial: This makes roughly 1.5 litres.
300g fresh mint, washed, which is basically several big bunches
1 litre of water
1.2kg sugar(Yes you can reduce or increase quantities proportionally).
Chop up the stems of mint roughly and bruise it.
Boil the water and pour over the mint in a bowl, and steep the mint in the water for 24 hours, covered.
The next day, wring out the mint getting all the drops of juice out.
Dissolve the sugar into it then boil for 2-3 minutes.
Cool and bottle.