Dry the prawns and add some salt and pepper. Warm 1 tablespoon of coconut oil in a large skillet over medium-high heat. Sear the prawns for 30 to 45 seconds on each side until they turn a lovely pink; be careful not to overcook them. Transfer them to a dish.

In the same pan, add the rest of the coconut oil. Add the mustard seeds to the heated pan and let them pop. Toss in the curry leaves, green chillies, and lemongrass (if using). Gently cook until the aroma wafts, which should take around one minute. Reduce the temperature and add the cherry tomatoes with turmeric and coriander powder. Give the tomatoes a minute to soften while retaining their juices. Don’t overmix everything.

Add the coconut milk and reduce the heat to a low simmer. Add salt and pepper according to your taste. Toss in the cooked pasta along with a splash of the pasta water that was set aside.

Put the prawns back in the pan and cook until they're just warm. Add the chopped coriander and season with salt and pepper to taste.

Serve right away. Garnish with more coriander and lime wedges, and drizzle with chilli oil.