yield: Makes 8 first-course servings

• 2 navel oranges (1 pound total)
• 2 fennel bulbs, stalks discarded and bulbs halved lengthwise
• 1 1/2 tablespoons white-wine vinegar
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 1/4 cup olive oil
• 2 heads escarole (2 pounds total), dark outer leaves discarded and pale green and yellow inner leaves torn into bite-size pieces

Finely grate enough zest from 1 orange to measure 1 tablespoon. Cut peel, including all white pith, from both oranges with a paring knife. Cut segments free from membranes, then cut segments crosswise into 1/2-inch pieces.
Cut out and discard core of each fennel bulb, then cut bulbs crosswise into thin slices.
Whisk together vinegar, zest, salt, and pepper in a small bowl until salt is dissolved, then add oil in a stream, whisking until combined well.
Toss escarole, fennel, and oranges with dressing in a large bowl until combined well. Season with salt and pepper.