Heat the crab shell and vegetable oil in a pan to warm and set aside to infuse.
Strain the crab-flavoured oil into a jug.
Whisk the egg yolks in a bowl.
Gradually whisk the strained oil into the yolks a little at a time.
Stir in the Dijon mustard and brown crabmeat then set aside.
Mix white crabmeat, spring onion, mooli, coriander, lemon juice, soy sauce, and oyster sauce in a bowl.
Roll the mixture into 12 filo pastry sheets while tucking in the edges.
Preheat the deep fat fryer oil to 180°C.
Deep fry spring rolls until golden-brown and drain on kitchen paper.
Boil 250ml water, sugar, vinegar, star anise, cardamom, cinnamon, and chilli, then cool for the dressing.
Toss spinach leaves in sesame oil and sprinkle with sesame seeds.
Serve spring rolls over spinach and mango cubes coated in the spiced dressing with a spoonful of mayonnaise.