Rinse spinach carefully, but leave branches attached to roots. Drain thoroughly and pat dry. In small bowl, combine soy sauce, lemon juice, and garlic. Heat oil in wok over high heat. Add spinach. Stir with pancake turner to gently keep spinach moving. Cook about 1 minute, until tender. Remove from heat. Sprinkle with soy mixture and toasted sesame seeds. Season to taste with pepper. Mix to blend.