Dock your pie crust with a fork and pre-bake it in a 350 degree oven for about 10 minutes, or until it's golden. Set aside to cool.
In a medium, heavy-bottomed saucepan, place the coconut milk and the cornstarch. Whisk well to combine. Turn the heat on to about medium, and bring up to the boil, allowing the milk to thicken. Add the sugar, salt, lime zest, lime juice, and vegan butter, and whisk well to combine. Bring up to the boil again, allowing it to bubble and thicken. NOTE: if the colour is too pale, you could add a couple drops of green food colouring. This won't affect the taste, just the esthetic look of the pie.
Pour the hot curd into the prepared pie crust, and let set in the fridge overnight (or at least for a few hours).
To make the meringue, place the aquafaba, sugar and cream of tartar in the bowl of your stand mixer (alternatively, you can do this with a hand mixer, it just means you have to stand there and whip it for 10 minutes). Whip for 2 minutes on the lowest setting to combine, then turn up to medium for 2 minutes, and finally to high for about another 4-6 minutes, until the meringue is light and fluffy, and holds a peak.
Spread the meringue on top of the pie, and torch to brown. Serve immediately.