Mix the prawns with the with the soy sauce, lime zest & juice, garlic chilli, and ginger. Add 1 Tbsp of water and marinate for 15 minutes.
Line a bamboo steamer with baking paper. Pour a glass of water in the wok, bring to the boil.
Place the bamboo steamer in the wok, making sure that the base does not touch the water. Pour the marinated prawns into the bamboo steamer. Put the lid on and steam for 5 minutes.
In the meantime, blanch the sugar-snaps in boiling water for 2 minutes, drain and put them in a large serving dish. Add the spring onion and coriander leaves.
When the prawns are ready (i.e. changed their colour to pink), add them to the sugarsnaps.
Heat the two oils, when they start to smoke, approx. after a minute, pour it over the prawns. Let it sizzle for a moment, then mix well and garnish with sesame seeds.
Serve warm or at room temperature.