Sit a duck breast between 2 sheets of cling film on a chopping board. Use a rolling pin to bash the duck until it is 0.5cm thick. Repeat with the other breast, then put them both in a dish. Mix the curry paste with the lime zest and juice, and rub all over the duck. Leave to marinate at room temperature for 20 mins.
Meanwhile, tip the rice into a small saucepan with some salt. Pour over the coconut milk with 150ml water. Bring to a simmer, then cover the pan, turn the heat down low and cook for 5 more mins. Stir in the peas, then cover, turn the heat off and leave for another 10 mins. Check the rice - all the liquid should be absorbed and the rice cooked through. Boil the kettle, put the beansprouts and red onion in a colander and pour over a kettleful of boiling water. Stir the beansprouts and onion into the rice with the pineapple, chilli and coriander stalks, and some more salt if it needs it, and put the lid back on to keep warm.
Heat a griddle pan and cook the duck for 1-2 mins each side or until cooked to your liking. Slice the duck, stir most of the coriander leaves through the rice with a fork to fluff up, and serve alongside the duck, scattered with the remaining coriander.