Napa+Cabbage,+Tomato,+and+Avacado+Salad

Beat the heat with this amazing, super light salad! Its easy to make, great for you and oh so delicious. Nothing to feel guilty about here!
 * INGREDIENTS **
 * 1 teaspoon finely grated fresh lemon zest
 * 1 tablespoon fresh lemon juice
 * 1 teaspoon Dijon mustard
 * 1/4 teaspoon salt
 * 1/2 teaspoon black pepper
 * 1/4 cup extra-virgin olive oil
 * 1 (1-pound) Napa cabbage *
 * 1 (6- to 8-ounce) firm-ripe avocado
 * 3/4 pound tomatoes, halved *

Tear enough cabbage leaves from ribs into bite-size pieces to measure 7 cups, reserving thick ribs and remaining leaves for another use. Quarter avocado lengthwise, then pit and peel. Cut into 1/2-inch pieces. Toss cabbage leaves, avocado, and tomatoes in a large bowl with just enough dressing to coat.
 * //PREPARATION//**  Whisk together lemon zest, juice, mustard, salt, and pepper in a small bowl until smooth, then add oil in a stream, whisking until emulsified.