Instructions

If you purchased your periwinkles from a live tank at your local Chinese fish market, then all you need to do is give them a quick rinse since they purge sand in the live tank.
After we gathered our periwinkles, we gave them a good rinse and then stored them in a bowl without any water overnight in the refrigerator. The next day, we soaked them in cold water for 10 minutes, and gave them another good rinse. Pour the periwinkles into a colander to drain.
Heat your carbon steel wok or metal pot over medium heat. Make sure you don’t use a non-stick pot, or you will risk damaging your nonstick coating. The shells on these periwinkle snails are thick and hard!
Add 2 tablespoons vegetable oil and 2 teaspoons chopped fresh ginger.
Stir the ginger for 10 seconds to infuse the oil, and add 1 tablespoon of chopped garlic, ¼ cup chopped onion, and 1½ tablespoons ground black bean and garlic sauce.
Stir everything together until combined, and add the periwinkle snails.
Turn the heat up to high, and stir the snails into the sauce for 10 seconds. Add 4 tablespoons of Shaoxing wine. Continue stirring at high heat for another 15 seconds, and add sesame oil, sugar, soy sauce, and dark soy sauce. Stir and cover the pot or wok.
Cook for another 4 to 5 mins, covered, depending upon your stovetop heat. The periwinkle snails and sauce mixture should be steaming when you take off the cover. Add white pepper.
Next stir up your cornstarch slurry until it’s well combined. (Remember that cornstarch separates from water after sitting for more than a minute.)
Pour the cornstarch slurry over the periwinkle snails and use your spatula to quickly mix the slurry with the sauce.
Add the scallions, and continue to stir for another 30 seconds. Transfer to a bowl to serve.