How to Make It
Place grapes in a small heatproof bowl. Stir together muscat vinegar, sugar, and 2 teaspoons salt in a small saucepan. Bring to a boil over high, and cook, whisking often, until sugar dissolves, 2 to 3 minutes. Pour vinegar mixture over grapes. Refrigerate, uncovered, until pickled, about 4 hours. Drain, reserving 2 tablespoons grape pickling liquid.
Fill a large bowl with ice water. Remove celery leaves from stalks; reserve leaves for garnish. Peel stalks, and cut in half crosswise. Using a mandoline, slice stalks lengthwise into thin strips; place strips in bowl of ice water.
Cut fennel bulb in half lengthwise; remove and discard core. Cut bulb into wedges, and thinly slice on mandoline. Place in ice bath with celery.
Whisk together olive oil, lemon juice, honey, pepper, reserved grape pickling liquid, and remaining 11/2 teaspoons kosher salt in a medium bowl. Set dressing aside.
Drain celery and fennel; transfer to a plate lined with paper towels. Pat completely dry. Gently toss together celery, fennel, and dressing.
To serve, spread goat cheese evenly across a serving platter or divide among 8 salad plates, and sprinkle evenly with lemon zest. Top evenly with celery-fennel salad, pickled grapes, peppery greens, celery leaves, fennel fronds, and, if using, shiso leaves. Serve immediately.
Wine grapes are available from melissas.com and can be substituted with Champagne grapes, muscadines, or any sweet table grape. Look for fresh shiso in the refrigerated section of Asian grocery stores.