The day before cooking the laksa, pat the duck breasts dry, then season the duck skin liberally with salt and allow to dry out, uncovered in the fridge overnight. Remove from the fridge 1 hour before cooking.
In a large saucepan, heat the oil over medium high heat. Add the onion, lemongrass, lime leaves, chilli,coriander roots and eggplant, then cook, stirring, for 2-3 minutes.
Add laksa paste, stock, coconut milk, fish sauce and sugar. Bring to the boil, then reduce heat to medium and cook for 10 minutes or until reduced. Add the beans and fried tofu puffs.
Meanwhile, pat the duck breasts dry again. Place in a cold steel pan, skin side down and cook for 10-12 minutes over low heat to render the fat. Gradually turn the heat up from low to high. Turn the duck breasts over and cook for a further 5 minutes. Allow the duck breasts to rest for 10 minutes before slicing.
Cook noodles according to the packet instructions, then drain. Divide noodles among two bowls, ladle over laksa broth, followed by the sliced duck, then garnish with bean sprouts, herbs, extra chilli and lime wedges.