-
1
Bring the stock to a full rolling boil in a wide pot over high heat. The surface should be in vigorous motion — still and tepid stock will not absorb the starch cleanly.
-
2
Pour the sweet potato starch slurry into the boiling stock in a slow, steady stream, stirring constantly. Continue stirring until the broth thickens to a deep amber, near-gravy consistency — it must coat the back of a ladle heavily and fall in a slow ribbon, not a running drip. This is where the dish lives or dies: under-thickening produces thin soup; the broth must be very thick.
-
3
Drain the pre-soaked mi suah and lower it into the thickened broth. Cook for 30 seconds only, stirring gently. The noodles are done when they have softened completely and have begun to disappear into the starch — they should offer no resistance when pressed between finger and thumb.
-
4
Add the shucked oysters to the broth and poach for 60 seconds exactly. They are done when the edges just begin to ruffle and the bodies turn from translucent to a just-set, creamy opacity — remove from heat immediately.
-
5
Ladle into deep bowls. Drizzle black vinegar over each portion — the acid should be detectable on the nose before the bowl reaches the table. Finish with a spoonful of pounded raw garlic and chili sauce placed directly on top. Serve immediately; the condiments are stirred in by the diner at the moment of eating.