Grandma Smith, apple pucker, and jolly ranchers all knew the same thing - sour green apples are awesome!
Steep time: 2-3 days for the crispness of the apple to mellow. A hint of creaminess develops over the first week.
Mixer's suggested options: 1.2x flavor, 0x sweet. The sourness scales with the flavor level, leave an order note if you would like that changed. The sourness and the apple flavors are both rather sweet tasting, only get the sweetener if you want it really sweet.
As you may well be aware Open source vapor has been forced to close their doors due to regulations there... this recipe is 100% theirs and was made public by them on their site, all i have done is copy over to ELR to ensure its not lost.