- In a large mixing bowl, whisk together the mayonnaise, balsamic vinegar, and sugar until smooth and creamy. This creates a tangy-sweet dressing that perfectly balances the salad's fresh flavors. 
- Add the broccoli florets, halved grapes, and finely diced red onion to the bowl. Toss everything thoroughly to ensure the vegetables and fruit are evenly coated with the dressing. 
- Gently fold in the chopped pecans, reserving a small handful for garnish. The pecans add a delightful crunch and nutty undertone to the salad. 
- Refrigerate the salad for at least 30 minutes before serving to allow the flavors to meld and the broccoli to slightly soften. When ready to serve, give the salad a quick stir to redistribute the dressing. 
- Sprinkle the reserved pecans over the top for a beautiful finishing touch, and enjoy this refreshing, crisp, and slightly sweet salad!