Heat a wok or large skillet over high heat. Add 2 tablespoons of the oil and heat for 30 seconds. Add the seafood and stir-fry until cooked through, 3 to 4 minutes. Transfer to a plate. Wipe out the pan. Reduce heat to medium-high, add the remaining oil, and heat for 30 seconds. Add the peas and water. Cover partially and cook, stirring occasionally, until bright green, about 1 minute. Add the spinach or watercress and the Lemon-Herb Sauce. When it starts to bubble, add the seafood. Stir-fry until warmed through, about 1 minute. Serve immediately over the rice.
Tip: Chicken or tofu can stand in for the seafood, and asparagus can substitute for the snow or sugar snap peas.