Making pie is easy. If you can make toast, if you can boil water, you already have all the skills you need to make a pie.

This is my instructable describing how to make more-or-less healthy fruit pie, using 4 ingredients and no sugar.

Step 1: Buy a Pre-made Pie Shell

Where I live, the mega-corporation Grupo Bimbo supplies "Tenderflake"-branded pie shells to every grocery store. Made with lard and flour, each box contains 2 pie shells, each in an aluminum baking pie plate. Choose a pie shell and buy it. My wife is vegetarian (lard is not an option), so I spend a little bit more money to purchase a vegan pie shell from a local organic grocery.

I wish that a company would distribute the classic vegetarian-but-not-vegan pie shell made with butter and flour.

If someone truly wanted to roll pastry from scratch, they already know how to make pie, and they will not be reading this instructable. For the rest of us, we will go to the grocery store and buy a pre-made pie shell.

Step 2: Buy a Bag of Frozen Fruit

I recommend to buy a heavy pound of frozen fruit. When fruit is in-season, the total available quantity of ripe fruit is greater than the quantity of fruit that consumers will buy. This oversupply guarantees the lowest prices for the fruit, and much of the surplus ripe fruit is frozen. The easiest way to get fruit at the peak of ripeness and the lowest price, is to buy frozen fruit.

In these photos, I use 600g of peeled fresh organic apples (they were in season). Normally I use 600g of frozen berries. A pound is 454g, so that's why I suggest a heavy pound. Feel free to make extra; the no-sugar-added fruit filling Is great on cereal, toast, meat. Deep dish pie shells will hold more like 1.5 lbs

Step 3: Buy a Thickening Agent

I use corn starch.

People on restricted diets will need to use their own thickening agent. Possible candidates include carrageenan, xanthan gum, gelatine, agar, pectin.

Step 4: Parallel: Bake the Pie Shell

Follow the instructions to bake your pie shell. Baking should take about 15 minutes. In my case, I put the shell into a preheated 375F oven, and pull it out at 12 minutes when it looks nice and toasted.

This shell-baking step and the following filling-cooking step should be performed in parallel (temporally coincident).

Step 5: Parallel: Cook the Filling

Choose your favourite cooking pot with a lid, and add a splash of water - just enough to cover the bottom of the pot. Bring to a boil, and then empty the bag of frozen fruit into the pot. Cover the pot with a lid and keep the heat on, stirring every couple of minutes so that nothing burns.

In the first couple of minutes, when the pie shell is only beginning to cook and the fruit is still frozen, mix 2 tablespoons of cornstarch with about the same amount of *cold* water. The chemistry of corn starch is such that the powder starch easily dissolves in cold water, and does not dissolve easily into hot water.

Remember to stir the fruit every couple of minutes, and peek at the baking empty pie shell in-between stirs to see if it's browning nicely. If there are any bubbles of steam pushing up the bottom of the pie shell, briefly open the oven and poke a fork into the middle of the pastry bubble to release the steam beneath.

In the pot, the fruit is heating up in the steam, releasing juice, and looking more and more like soup. We are waiting until the fruit is "occasionally blurping" (cookbooks describe this temperature as "a near-boil"). Once the fruit is "occasionally blurping", stir the fruit quickly while you steadily pour the corn starch solution into the centre of the stir. This solution of cold water and cornstarch is critical to making a pie filling that can be eaten with a fork, rather than a soup spoon. Keep the heat on and keep stirring, the boiling juice will cook the corn starch, the fruit soup will thicken until it resembles hot pie filling. At this point, remove the pot from the heat.

Step 6: Pour the Hot Fruit Filling Into the Cooked Pie Shell

I use a silicone spatula to empty the pot of fruit filling into the pie shell. My son prefers that I simply pour the filling into the pie shell and give him the cooled pot with a spoon for taste testing purposes.

The last step is to wait until the pie is cooled, and then to cut it into pieces of pie and serve. This waiting stage takes longer than cooking the pie itself, and I have to admit I am rarely able to wait this long before helping myself to a piece of pie.

I hope you enjoyed my first instructable, I'd appreciate feedback of all types.