Place the cashews in a heat proof bowl and cover with boiling water. Let sit for at least one hour to soften the nuts.
Preheat the oven to 350ºF / 175ºC degrees. Line an 8x8 baking pan with parchment paper.
Combine the crust ingredients in a mixing bowl. Mix well until it’s crumbly. Transfer it to the baking pan and press it into an even layer in the bottom of the pan. Bake for 16 minutes.
While the crust is baking, drain the cashews and add them to a high speed blender along with the sugar, coconut milk, lemon juice, cornstarch, lemon zest, turmeric and salt. Blend until smooth.
Pour the filling mixture through a sieve into a saucepan. Discard any solids.
Place the saucepan over medium heat and whisk continuously until the mixture begins to bubble and becomes thick like pudding.
As soon as the crust has finished baking, spread the hot filling on top of the crust and return it to the oven for another 15 minutes.
Remove from the oven and cool for 1-2 hours at room temperature, then transfer to the refrigerator to chill overnight.
Dust with powdered sugar immediately before serving.
Notes
To store: Once these vegan lemon bars have completely cooled and set in the refrigerator overnight, you can store them in the fridge for up to a week. Keep them covered in the baking dish or transfer them to an airtight container.To freeze: After chilling and cutting the bars, place them in a single layer on a baking sheet and freeze until solid. Once frozen, transfer the bars to a freezer-safe container or a zip-top bag, placing parchment paper between the layers. They can be stored in the freezer for up to 3 months. When ready to enjoy, thaw the lemon bars in the refrigerator overnight before serving.