In a bowl, combine the corn oil and ginger and let stand at room temperature for at least 2 hours.
Strain the oil.
With a very sharp knife, cut the tuna into ⅛-inch dice.
In a large bowl, combine the tuna with 3 tablespoons of the ginger oil, 3 tablespoons of the cilantro, jalapeño, wasabi, sesame seeds, scallion, and lemon juice. Mix gently and season with salt and pepper.
Stand a 1 ½-inch-tall by 2 ¼-inch-round mold or biscuit cutter in the center of a salad plate. Fill the mold with tuna tartare, pressing gently. Lift off the mold. Repeat with the remaining tartare.
Drizzle the remaining ginger oil around each tartare and sprinkle with the tomato, the remaining tablespoon of cilantro, and a squeeze of lemon juice. Stand 5 potato chips in a circular pattern in each tartare and serve immediately.
