Set a heavy non-aluminum stockpot over high heat until hot enough to evaporate a bead of water. Add the oil to the pot, swirl to coat the bottom, then reduce the heat to medium-high. When the oil is hot enough to sizzle a bit of scallion, add the scallion and ginger, adjusting the heat so they sizzle without scorching. When fully fragrant, about 10 to 15 seconds, add the ham or crab. Stir briskly to combine, about 10 seconds, then add the wine. Wait a split second for it to "explode" in an aromatic hiss, then toss the meat briskly several times and immediately add the stock. Stir to blend, add the corn, and stir again. Bring the mixture to a near-boil over moderate heat. Stir frequently and watch that the heat does not climb too high, lest the corn burn.