Start with the prawns. Bring a saucepan of lightly salted water to the boil. Blanch the prawns for 30 seconds, drain and cool in iced water. Remove the heads, peel and devein, and place them on a chopping board.
Brush with Sriracha sauce and season with black pepper and extra chilli flakes (optional).
Heat a large griddle pan over a medium-high heat. Grill the prawns for 1 minute on each side, then remove from the pan and allow to cool slightly.
For mango salsa: Peel and finely dice the mango, place in a bowl and mix with the red onion, pomegranate, tomatoes, ginger, lime juice and coriander, and season to taste with salt and pepper.
Place a metal pastry ring on a serving plate and fill it with mango salsa. Top with grilled shriracha prawns, sprinkle with lemon zest and chopped coriander and serve immediately.