First, wash your yu choy. We recommend that yu choy and all leafy green vegetables be washed three times to rid the leaves and stems of hidden dirt and sand. Once the veggies are cleaned and draining in a colander, bring a large pot of water to a boil.
While that’s happening, heat 1 tablespoon of oil in a small saucepan over low heat for 30 seconds. Stir in the oyster sauce, soy sauce, sesame oil, and white pepper. Bring the mixture to a simmer, then immediately turn off the heat and set aside.
Once the water is boiled, add 1 tablespoon of oil to the boiling water. Add in the yu choy and stir gently. The yu choy will turn dark green in color. The blanching process takes only 30 seconds, but if your yu choy has thick stems, or if you like your vegetables to be more tender, you may want to cook them a little longer—up to a minute or so. Feel free to fish out a piece to taste (like you'd do when cooking pasta) if you're unsure.
Once they are ready, use a pair of tongs or chopsticks to remove them from the pot and arrange on a dish lengthwise. After you have plated the hot vegetables, some water may have drained off onto your platter. Be sure to carefully pour this off, or your sauce may be watery.
If the veggies are long, feel free to take kitchen scissors and cut them in half. But you can also leave them as is. Pour the warm sauce over the veggies and serve!