Extract salted egg yolks. Steam for 8-10 minutes over medium heat. Set aside to cool.
Remove the tips from the bitter gourd, before cutting into quarters. Scrape off the seeds and the white flesh. Slice about 0.5cm thinly. Set aside.
Heat oil for deep-frying for 10 minutes over medium heat.
Mix flour and cold water until cohesive. It should be thin enough to coat the back of a spoon. Add 1 tbsp of flour or water until the consistency is reached.
Generously coat bitter gourd with the crispy flour batter.
When the oil is hot, gently add the bitter gourd and fry for 5 minutes, or until golden brown on one side. I fried mine in 2 batches. Turn it and fry for another 4 minutes. Remove from the heat with a strainer to drip off the excess oil, and rest on a cooling rack.
Mash the cooled salted egg yolks to fine pieces. Strip all the curry leaves from the stems and set aside.
Add cooking oil for frying into the wok, butter and curry leaves. Fry until all the butter has melted and the curry leaves have curled up.
Add all the salted egg, and fry in the wok, stirring quickly for 15 seconds, or until the foam as expanded to triple its size.
Switch off the heat, and add the crispy bitter gourd. Stir quickly to coat the bitter gourd with the salted egg sauce.
Remove from the wok and serve immediately.