Received fresh green beans from friend who gardens. Cooked them in water seasoned with onion, salt & pepper. Have cooked for about 1-1/2 hours on medium heat - they are stringy & tough. What did I do wrong or is it just the beans? Any chance they will become tender if I cook them longer? They had seemed too tough for how I usually prepare them - lightly sauted in olive oil with garlic, etc , so thought I'd prepare them southern style, cooking longer. Any ideas, or do I just pitch them out?