Wash the 2-3 mountain apples, cut in half, remove the seed, cut into quarters and then freeze

Put frozen Mountain Apples into the blender with 1 cup of water.
Blend into a juice.
If it's too thick, eat it like a sorbet, or add more water until it's like a juice.
I feel like it's sweet enough as it is, but if you need it sweeter you can blend in sugar to taste.

If you're in a rush, just put everything in the blender and don't freeze the mountain apples. Add ice to chill it.
Or blend in ice cubes and you'll have something like a granita.