To purge the clams of sand and grit, fill a large bowl with the cold water, and add the sea salt. Stir until dissolved (salinity should be about 3.5%). Add the clams, and allow them to purge for at least 1 hour on the counter (or up to 20 hours in the refrigerator). Scrub your clams well to remove any surface grit from the shells.
Heat the oil in your wok over medium high heat, and add the ginger and the white parts of the scallions. Cook for 30 seconds.
Increase the heat to high, and add the clams. When the wok has heated back up, add the Shaoxing wine, and immediately cover the wok. Reduce the heat to medium, and cook until about 75% of the clams have opened (you can peek under the lid), about 5 to 6 minutes, depending on the size of your clams.
Meanwhile, mix the cornstarch and water to create a slurry.
Uncover the wok. Add the garlic, Thai chilies, oyster sauce, and dark soy sauce. Stir to combine, then stir in the cornstarch slurry, which will thicken the sauce.
Add the Thai basil and the green parts of the scallions, and stir-fry just until the herbs are wilted. By now, all the clams should be open—discard any that did not open and serve immediately with a squeeze of lime if desired.