Clean green beans and cut into 2-3 inch lengths. Chop onion and garlic and heat extra virgin olive oil (or vegetable oil if you don't have any) in a large skillet on medium heat. Place garlic and onion in pan and saute for a minute or two, just until they begin to turn translucent (I add some salt and pepper to the onions & garlic to season them also).
Add the green beans to the pan, sprinkle some balsamic vinegar or Garlic Red Wine Vinegar on top, season to taste with sea salt and coarse ground pepper and toss to coat well.
Cover with a lid, turn down heat to medium/low and continue to simmer for about 20-25 minutes, tossing occasionally to cook evenly.
The green beans are done when they are tender. Top with dots of butter, toss and they are ready to serve. These are delicious when served alone as an appetizer or with just about anything else as a side dish!