Preheat your oven to 350°F (175°C) and line a 9x13 inch baking dish with parchment paper.
In a medium mixing bowl, combine the melted vegan butter, cane sugar, flour, salt, and vanilla extract. Mix until it forms a crumbly mixture.
Pour the mixture into the baking dish and press it down evenly. Bake for 20 minutes or until the edges are lightly browned.
While the crust is baking, heat a large saucepan over medium heat. Combine the lemon juice and zest, coconut milk, sugar, cornstarch, and turmeric. Whisk continuously until the sugar dissolves, the corn starch is absorbed, and the sauce thickens.
Once the crust is done, remove it from the oven and pour the lemon mixture on top. Spread it evenly with a spatula.
Bake for an additional 20-25 minutes or until the edges are golden brown and the filling is set.
Remove from the oven and let it cool down to room temperature for 1-2 hours. If you have time, transfer it to the refrigerator to cool and set it for an additional 2 hours.
Once cooled, dust with powdered sugar and cut into squares.