How to Make It
In a large bowl, whisk the oil with the lemon juice, ginger, garlic and the 2 tablespoons each of scallions and sesame seeds; season with salt and pepper.
Fill a bowl with ice water. In a large saucepan of salted boiling water, blanch the zucchini for 30 seconds. Drain, then transfer to the ice water to cool. Drain well and pat thoroughly dry with paper towels. Add the zucchini, watercress and chicken to the dressing in the bowl and season with salt and pepper. Toss to evenly coat. Garnish with scallions and sesame seeds and serve.