Prepare crab: See separate tutorial for how to clean and cut a whole crab. You will end up with: 1) Crab pieces; and 2) Reserved tomalley ("crab mustard", Note 8) and crab juices in a separate bowl. This is a key "secret ingredient" used to flavour the sauce.

Chilli paste: Place ingredients in a small food processor or Nutribullet. Blitz until it's a fairly smooth paste.

Sauté belachan: Heat oil in a large pot over medium-high heat. Add belachan and cook for 2 minutes, stirring constantly. It will smell pungent (to put it mildly), but have faith! It will mellow and transform!

Cook off chilli paste: Add chilli paste and cook, stirring, for 3 minutes.

Add tomato passata: Add tomato passata and cook, stirring regularly, for 4 minutes.

Add remaining sauce ingredients: Add sweet chilli sauce, ketchup, water and stir to combine.

Add claws: Add the crab claws first (they take longer to cook), stir to coat in sauce. Bring to a boil, then reduce heat to simmer. Cover with a lid and cook 3 minutes.

Add "crab mustard" and juices: Add the reserved tomalley ("crab mustard") along with all the crab juices.

Add remaining crab pieces: Remove lid, add remaining crab pieces and any juices that have collected in this bowl. Stir pieces to coat, put the lid back on and cook for 7 minutes.

Remove crab: Use tongs to remove crab pieces into a bowl.

Egg ribbons: With the sauce still on the stove, and while stirring in a circular motion, pour the egg in a thin stream into the middle of the pot. This will create little ribbons of egg in the sauce that is traditional and look lovely.

Vinegar: Stir in vinegar.

Return crab: Return the crab pieces into the pot, gently stir to coat in the sauce.

Transfer crab pieces into a large serving plate or shallow dish. Pour over all the sauce from the pot. Garnish with coriander and green onion.

Serve with golden mantou buns (steamed and fried Chinese buns, traditional - Note 7), or homemade brioche (ultimate sub!), baguette, crusty bread or dinner rolls. Alternatively serve with rice on the side.

How to eat: Be prepared to get messy! Dive in for the claw (the prime piece!). Use crab or nut crackers to break the shell (or a meat tenderiser or hammer - anything to get to that meat!!) and reveal hunks of sweet juicy crab meat. Dunk generously in sauce and devour.

Leftover Sauce: You will have leftover sauce. It's loaded with flavour so save it, it's precious! See in post for ideas for how to use.