Add the remaining 1 1/2 tablespoons of oil to the wok along with the tangerine zest mixture and cook until fragrant, about 30 seconds. Add the zucchini, squash, carrot and water chestnuts and cook until the vegetables are crisp-tender, about 4 minutes. Stir the tangerine sauce and add it to the wok. Cook the sauce until slightly thickened, about 30 seconds. Return the scallops to the wok, stirring just until heated through, and serve.