Green beans are full of vitamins and minerals and are not very expensive. They appear often on menus and at family dinners but usually are soggy and bland. There are not much vitamins left in them.
Green beans, like pasta, need lots of boiling water and then a short boiling time.
Putting the beans in some water with salt, heating to boiling point and cooking for several minutes is a recipe for grey beans without taste. Generations of school children ate those in the canteen. Many an office cafeteria will serve them that way as well.
Of course you need fresh beans to start with. I had some from a friend with a large garden. I cut off both ends, removed any string, and washed in cold water.
In a pan I had six litres of water with some salt and took that to boiling on a high flame. I had prepared a bowl with cold water and ice cubes. Then I put the beans in the boiling water and waited a few seconds for the water to return boiling again. (That is why the volume of water is important, the lesser the volume the longer it will take to resume boiling because volume of the colder beans will be relatively more important).
I let it boil for three minutes, drained and put in the bowl with cold water. Do not remove it from the water until the beans have become lukewarm. Take the beans by hand from the water so that any remaining tops, string, surviving dirt and seeds stay in the bowl.
You can now put them aside for later or use them immediately.
Now add garlic and tomatoes
I had some sliced garlic in butter in a large skillet and added the beans to that. Then I stirred for some minutes and added chopped tomatoes. I continued stirring, not too long so that the tomatoes would not turn into a mush, and served.
The large quantity of water used may be a problem, ecologically speaking. But you do not have to throw it away. You can use it to cook other things in, after filtering, use it as cleaning water. Or give it to a pet or take it out in the garden and water the bean stalks, for instance.