Prepare the prawns
Remove the heads from the prawns, keeping them aside for the broth.
Peel the shells from the bodies, leaving the tails intact.
Using a sharp knife, make a shallow slit along the back of each prawn. Use the tip of your knife or a toothpick to gently remove the intestinal tract.
Repeat with the remaining prawns and set aside.
Prepare the lemongrass
Trim the top and bottom of the lemongrass and remove any dry outer layers.
Using the back of your knife, bruise the lemongrass by firmly hitting it a few times to release its aromas.
Cut into large pieces.
Fry the prawn heads
Heat a little neutral oil in a pot or claypot over medium-high heat.
Add the prawn heads and a pinch of salt.
Fry for 3–5 minutes, pressing down on the heads occasionally to release their juices, until they're bright orange and fragrant.
Make the tom yum broth
Add the bruised lemongrass and fry for another minute.
Pour in the water, then add the kaffir lime leaves and Nam Prik Pao.
Bring everything to a boil, then reduce to a gentle simmer.
Simmer for around 20 minutes to allow the prawn heads and aromatics to infuse the broth.
Strain the broth to remove the prawn heads, lemongrass and kaffir lime leaves, then return the broth to the pot.
Cook the toppings
Bring the broth back to a boil.
Add the prepared prawns and cook for 3–4 minutes, or until they're pink and cooked through.
Remove the prawns from the broth and set aside.
Add the frozen shrimp or lobster balls and cook according to the packet instructions, then remove and set aside with the prawns.
Season the broth
Add the noodle seasoning packet, lime juice, fish sauce and sugar to the broth.
Give everything a good stir and taste before adding the noodles. Adjust the balance of sour, salty, sweet and spicy flavours to your liking.
Cook the noodles
Add the noodles to the broth and cook for around 1–2 minutes, or until they have just started to soften.
Add the egg whites and evaporated milk, then stir well.
Continue cooking for another 1–2 minutes, until the noodles are cooked and the broth is creamy and fragrant.
Add the toppings
Add the noodles and broth to a large bowl . Then top with the crispy pork belly, cooked prawns, shrimp or lobster balls, coriander, Thai basil, fresh chilli and lime slices.
Finish with the raw egg yolk in the centre, or skip if you prefer, and dig in while everything is hot and soupy.
