Wash and dry the lettuce. Cut into bite-sized pieces. Add the celery. Chop the red onion and add it to the bowl. In a heavy bottom frying pan, combine the sugar and almonds. Cook until the sugar is melted and coats the almonds. When the almonds are cool to the touch, break them apart and place them in a separate dish. If you leave them to cool in the frying pan, they will stick together and you may not be able to separate them.
Once cool, add to the salad. Top with the mandarin oranges.
Combine all ingredients in a jar with a tight fitting lid and shake vigorously.