In a small bowl whisk together dressing ingredients.
Place red onions in baking dish lined with foil. Drizzle with 2 tablespoons of prepared dressing and toss well. Cover tightly with foil and bake at 350 degrees F for 30 minutes. Remove from oven and let cool.
Mix 1 tablespoon of olive oil with crushed garlic. Brush onto bread slices. Broil or grill bread for 1-2 minutes on each side until toasted. Cut bread into strips about 1/2 inch wide. Place bread, roasted onions, arugula, fennel, bell pepper, pinenuts and grapes in large bowl, and toss with remaining vinaigrette. Sprinkle with Parmesan and serve.