Prepare the suey choy by cutting in quarters lengthways through the stalk, then cut crossway in 1-inch (2 1/2cm) slices.
Heat the Dutch oven to medium-high heat then add the suey choy, garlic, and salt. Place the lid on the Dutch oven to stop the moisture from leaving (this is what steams to suey choy). Leave at a low temperature for 10 minutes, then test the firmness. When cooked it will be tender, but not mushy.
Serve immediately sprinkled with red pepper flakes, if desired.