Using a pestle and mortar, pound together coriander roots, garlic and peppercorns. In a wok, heat peanut oil and peppercorn mixture and onion and stir-fry for 1 minute.
Add pork, stir-fry for 1 minute the stir in prawns for 45 seconds. Quickly stir in fish sauce, then transfer mixture to a bowl. Using absorbent.
Add vegetable oil to wok and place over medium heat. In a small bowl, beat eggs.
Spoon egg into a cone of grease proof paper with a very small hole in pointed end. Move cone above surface of pan, so trail of egg flows onto it and sets in treads. Quickly repeat, moving in another direction directly over threads. Repeat until there are 4 crisscrossing layers of eggs.
Using a spatula, transfer nest to absorbent kitchen paper. Repeat with remaining egg to make more nests. Place nests with flat side facing downwards. Place 2 strips of chili to form a cross on each nest.
Top with coriander leaves, them about 1 tablespoon of pork mixture. Fold nests over filling, turn over and arrange on serving plate. Garnish with coriander sprigs.