Don't leave them to soak, but you can let them sit in acidulated water for five minutes or so then drain them. They will keep OK for a few hours. Do an experiment today with say one apple to see how long you are happy with them.

You can peel and slice them now. Give a quick dunk in salt water and freeze them in Ziplocs. (Salt water prevents them from getting brown.) When you're ready to make the pie, use the defrost setting on the microwave to thaw.

Crush a Vitamin C tablet in water & skip the salt. Much cheaper than Fruit Fresh & is what I use to keep any fruit I'm canning from darkening! Crush a 250 mg tablet between 2 spoons & add to about qt of water. No taste & just drain well or lift out to make pie. Why not make pie or tart day before?

This may seem like unwanted advice, but here goes. Buy yourself an advance Christmas present and get an apple peeler! Best investment I ever made!! I use apples a lot and since I have gotten mine I make more pies and cakes and applesauce than ever before. And the job I dislike the most take only a few minutes. I'm not normally a gadget person but I love this one. With an apple peeler, an apple tart will be a breeze! Here's a photo of mine. {{gwi:2135496}}

And just make the tart day before, put in the fridge and then bring to room temp. before serving. It will be fine. Well, I dunno, maybe I just love pie and am not that picky!

Thanks everyone,
Funny.......I do have that peeler! I forgot about it.
I wouldn't hesitate to make this the day before if I used a pie crust........but I don't think the puff pastry I want to use would hold up so well a day ahead. Can you tell I'm feeling a bit overwhelmed with the holidays? haha
I'm even considering a Marie Callender's frozen pie. I've heard some of them are Vegan. I just have to make a few compromises, or I'll be crazy. I guess a lot of my self esteem is tied up in my home-cooking. But what good is self-esteem if you go crazy? :)

You might be able to find a vegan pre-prepared pie crust, either in a pan or refrigerated. I know some are made with lard but some are made with all vegetable shortening. I know this because I had to find one to bring to a kosher party once. That way you can whip together a tart in about 15 min! Or as some have suggested, a press-in crust which you can make ahead, and then whip up the apples really quick. OR, do what I do and mix frozen peaches with frozen raspberries, or a mix of berries and cherries, etc. and have everyone rave about your "home made" pie! They sell lots of kinds of frozen fruits for pies in the freezer section of most groceries. Also pre-made pie crust. Just check the labels, a lot of them are made with hydrogenated vegetable oils. Not the most healthy, but then it IS pie! You can make strawberry blueberry tarts or something like that with puff pastry too. Buy some flavored cream cheese, spread it on the bottom and then put some sweetened frozen berries on top and bake. Don't sweat the apples, they are not the only fruit for a tart! I make a crisp that is a mix of sweet cherries, dried cherries, fresh cranberries and dried cranberries. The sweet and tart elements combine perfectly. Plus it is vivid red, good for the holidays. If you have your heart set on apples, mix it with frozen strawberries or frozen blackberries or raspberries. Half as much peeling!

This post was edited by lpinkmountain on Wed, Dec 17, 14 at 13:36

I use tart pastry. 8 oz. cream cheese, 1 1/3 c butter 2 2/3 c flour Mix well. Line tart pans. I've made lemon tarts & pecan tarts with this pastry, think it would work for apples also.

But of course, if OP needs vegan, then cream cheese and butter are not suitable.