Home-Style Salad Dressing

1 cup mayonnaise
1 small onion, cut into wedges
2 tablespoons sugar
2 tablespoons white vinegar
2 tablespoons ketchup
1 teaspoon salt
1/2 teaspoon celery seed
1/3 cup vegetable oil
Salad greens and vegetables of your choice
Crumbled blue cheese

Place the first seven ingredients in a blender; cover and process until smooth. While processing, gradually add oil in a steady stream.

In a salad bowl, combine greens and vegetables; sprinkle with blue cheese. Serve with dressing. Refrigerate any leftover dressing. Makes 1-1/2 cups.