1. Heat oil in large frying pan at medium heat.
2. When oil is very hot, sauté onions until almost tan, stirring constantly.
3. Wash, drain, remove stems, and cut up string beans.
4. Add to frying pan and cook until tender, not firm, about 20 minutes or more. Stir often.
5. When string beans are tender, add walnuts to pan and mix together.
6. Remove from heat and let cool.
7. Place in food processor. Pulse until the ingredients are broken up. Process until smooth.
8. Continue to process, turning on and off until the mixture looks like chopped liver.
9. Add salt and pepper to taste.
10. Scoop into a small bowl, cover and refrigerate until cold.