1. In a small bowl mix the vinegar, oil, maple syrup and maple sugar together, and set aside.
2. In a larger serving bowl combine the green beans, kidney beans and onions.
3. Add the maple dressing to the beans and mix thoroughly.
4. Refrigerate in a glass container. Always best the next day. The salad can keep for several days.
* Maple syrup can be substituted for the maple sugar. Howerver, the mixture of oil, vinegar, and syrup should be brought to a boil and then removed from heat.