Mixed Greens with Walnut and Roast Onion Dressing

8 Cups torn assorted salad greens, washed
2 large onions, sliced into wedges
1 Cup olive oil
1 T. white sugar
1/2 cup chicken broth
1/3 cup sherry wine vinegar
1 cup toasted chopped walnuts
1/2 red onion, thinly sliced
Preheat oven to 400 degrees. Place onion cut side down on baking sheet. Drizzle with 2 tablespoons oil and sprinkle with sugar. Bake for 30 minutes. Turn onions over and bake until brown and carmalized, about 30 more minutes. Set aside to cool.
Place onions in food processor add remaining oil, broth, and vinegar. Puree until smooth and thick. Season, with salt and pepper. Cover and refrigerate until chilled.