Make the mango curd: put all the ingredients in a high-power blender and blitz until smooth. Taste and stir in more agave syrup or more lime juice, to taste.
Strain the pulp into a saucepan over a fine sieve and discard any solids.
Cook over low heat, stirring with a balloon whisk, until the curd thickens. Transfer to a jar and leave to cool completely. Seal the jar and chill in the fridge overnight.
Preheat the oven to 180°C (350°F). Spray four 15 (6 in) cake tins with cake release (or grease with vegan spread) and line the bottoms with baking paper.
Mix the coconut milk and vinegar and leave to stand for ten minutes. Sift the flour, baking powder and bicarbonate of soda together in a bowl.
Add all the ingredients, into a food processor or blender and process until the batter is completely smooth. Make sure to scrape the sides and bottom of the processor midway to ensure all the ingredients are well blended.
Divide the batter between the prepared tins and bake for 30-35 minutes, or until the cakes are springy to the touch and coming away from the sides of the tins. A skewer inserted in the centre should come out clean.
Leave the cakes to cool in the tins for 10 minutes the carefully turn out onto a wire rack to cool.
Add the lime juice in a measuring jar and top with enough water to make up 120ml (1/2 cup) liquid. Add to a saucepan together with the sugar and cook over low heat, stirring, until the sugar dissolves and mixture almost comes to a simmer. Transfer to a jar to cool (leftovers can be stored in the fridge for up to a week).
Brush a little of the syrup over the cakes and then cover loosely with cling film.
Add the vegan spread and icing sugar into the bowl of your stand mixer fitted with a paddle attachment. Mix on low speed to combine then increase the speed, gradually adding the strained passion fruit juice, until frosting is smooth. Transfer frosting to a piping bag fitted with a plain round tip.
Transfer the mango curd to a piping bag, snipping a small hole on the tip.
Sandwich the cakes with the frosting and mango curd, piping a ring of frosting on the perimeter of the cakes to encase the curd.
Add a thin layer of frosting over the top and sides of the cake and smooth using a side scraper. Place the cake in the freezer for 30 minutes.
Add another layer of frosting over the chilled cake, smoothing as before.
Peel ribbons off a ripe but firm mango, using a potato peeler. Arrange the ribbons in a concentric circle so that they resemble a blooming rose.
Sprinkle the cake with lime zest and add a few edible flowers as decoration.
Best eaten soon after assembled but it will keep for a day in the fridge for up to a day. Instead of self-raising flour, you can use plain (all purpose) flour and add 5 tsp baking powder and 1 tsp bicarbonate (baking) soda. Make sure your flour and raising agents are still fresh, otherwise you may end up with a dense bake.