This is a great way to use any leftover duck (or turkey or chicken). If you are making the duck especially for this curry I would recommend you cook it separately and use the method below.

Into a hot wok or large pan add the curry paste and allow it to sizzle for a couple of seconds.  Add the coconut milk and reduce the heat to a simmer.

Add the left over duck and stir though

Add all the veg together and stir though, allow to simmer for about 5 min stirring gently

Add the sugar, fish sauce and pineapple if you are using it and simmer for another 5 min

Serve with Rice ( thai jasmine rice is the best for this, its nice and sticky)

Its sound this simple because it really is!  The more you simmer it the thicker it will get so if you don't like it as runny as the Thai people like it just cook it for a little longer before you add your meat and veg.  Don’t get too hung up on quantities, its curry and left overs, you’re supposed to throw in whatever you have! As long as the ratio of paste to milk is the same its all good.