Lovely Layered Vegetable Tart

I've been on a squash and root veggie kick these past few weeks, with all these delicious, colourful items in season, I have been craving those fall colours in almost everything- from tree leaves (most of which seem to be carpeting our front garden these days!), to nail polish, to food!

I came up with this dish rather lazily- we had just had a beautiful bonfire in the crisp autumn air, and enjoyed a lovely apple pie outside. I was left with a defrosted pie crust to use, and a fridge full of veggies to fill it with. To celebrate all the colours of the season, and as a fun surprise, I made a layered tart-green, brown and.. purple! This is not your typical autumnal tart! You can experiment with other colours and flavours as the seasons change- perhaps a black garlic and green zucchini layered tart for Hallowe'en, or a charred red pepper layer topped with fresh mozzarella for a summery pizza style tart? I can't wait to see your creations!

Here I served this dish with a side of my Delectable Delicata Squash Rings for a dish packing an autumnal flavour punch! The recipe for those is available here:
https://snugglegrub.com/delicata-rings/

Ingredients
1 Pie crust- happily a lot of frozen pie crusts are vegan, but you can make your own without too much trouble- flour (typically all purpose wheat flour), and fat (typically butter or margarine) are the two main ingredients- you can adapt for gluten free or vegan options as you choose.
1 Courgette/ zucchini finely sliced
1 Onion- finely sliced
Balsamic vinegar- 1/2 tsp
salt- to taste
Any other seasoning you enjoy- I sprinkled a little Trader Joe's Chickenless Seasoning on the top of this for extra flavour
Potatoes- here I used 2 purple sweet potatoes and 1 russet potato

Method
First, bring a saucepan 1/2 full with water to a rolling boil
Pre-heat the oven to  350°F/ 180°C
Slice the onion, and add to a small frying pan to gently sauté with a little water, salt, and balsamic vinegar to enhance the sweetness, you should see the onion gently caramelise which is what works best here.
Peel the potatoes and chop into chunks, add to the water to cook through. Once soft, drain and mash the potatoes- this should result in a purple mash
Roll out the pastry to fill a pie dish, if making the pastry from scratch, or if you are making this with very wet ingredients, I'd recommend first blind baking the pastry- that is baking the pastry without any filling for 10 minutes to ensure the bottom doesn't go soggy! (Mary Berry would be proud!)
Spread the purple mash on the bottom of the pie, ensuring it is distributed fairly evenly. Add the caramelised onion layer, again spreading the onion evenly throughout the pie. Finally layer the courgette/ zucchini- I found it easiest to start in the middle with the smaller 'end' slices, layering towards the outside.
Crimp the pie edges by pinching your forefinger and thumb together on 1 hand, then pushing the pastry towards them with your index finger on the other hand.
Bake for 25 minutes at 350°F/ 180°C,.