For each serving, to order, in a wok or sauté pan, heat 1 tablespoon oil over high heat. Add 3 mushrooms and 2 shallots; sauté until mushrooms are tender and shallots are lightly browned. Add 1 teaspoon ginger; sauté briefly. Add 6 ounces gai lan and 2 tablespoons oyster sauce; simmer, covered, until gai lan is heated through. Garnish with ichimi togarashi.