01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang.
02 - In a medium bowl, combine flour, powdered sugar, and salt. Cut in cold vegan butter with a pastry cutter or fork until mixture resembles coarse crumbs.
03 - Press mixture evenly into the pan bottom and bake for 15 to 18 minutes until lightly golden.
04 - Combine citrus juice, zest, sugar, cornstarch, and turmeric in a saucepan; whisk until smooth. Stir in coconut milk.
05 - Cook over medium heat, whisking constantly, until thickened and boiling gently, about 5 to 7 minutes. Remove from heat and stir in vegan butter until smooth.
06 - Pour filling over the hot crust and spread evenly. Bake for 15 to 18 minutes until edges set and center jiggles slightly.
07 - Cool completely on a wire rack, then refrigerate at least 1 hour to firm up.
08 - Lift bars out using parchment overhang, dust with powdered sugar if desired, and slice into 16 bars.