Prep: 2. Chop scallions. Reserve dark green tops for garnish. 3. Whisk together mayonnaise, scallions, and vinegar. Season with salt and pepper. 4. Peel, seed and cut cantaloupe. 5. Thinly chop chard and transfer to a large bowl. 6. Cut chard stems and ribs crosswise into 2-inch pieces, thinly slice lengthwise, and add to bowl with chard. Make: 1. Just before serving, toss chard and cantaloupe; garnish with scallion tops. Serve with dressing.