Process flour, salt, and sugar in a food processor; pulse in coconut oil until sandy.
Add water gradually while processing until the dough holds together without overhydrating.
Wrap the dough in clingfilm, refrigerate for 30 minutes, then roll it out on a floured surface.
Fit the dough into a pie tin, crimp edges, refrigerate for 20 minutes, and preheat the oven to 180°C.
Prick the crust, line with parchment and weights, cover edges with foil, and bake for 10-15 minutes.
Check the base; bake an extra 5 minutes if needed, then cool fully.
Heat lemon curd ingredients (except butter) in a saucepan, whisking constantly until thickened; stir in vegan butter and cool.
Whip aquafaba in a stand mixer until foamy, gradually add ingredients, and whisk to stiff peaks.
Pour cooled lemon curd into the crust, leaving space for meringue; chill for 10 minutes.
Spoon meringue onto curd, pile high, and brown peaks with a kitchen torch or under a grill.
Serve immediately for best texture; refrigerate leftovers for up to a few days.