Wash the Greenstar apples and chop into large chunks. Add spigs of mint and prepare in steam juicer for some 20 minutes. Rinse a couple of swing-top bottles in hot soda water and then in hot water. Pour the juice into the bottles.
Pasteurise the bottles by keeping the temperature at a constant 70 degrees Celsius for another 25 minutes. This prevents the juice from fermenting and ensures a shelf life of over two years.