This is more of a friendly tip than a receipt as I know this vegetables may not be the easiest to work with.
To cook them perfectly you need to know what you’ll need. Besides the basic water and beans you will also need salt and different spices you decide to use. I like to add slices of lemon as they add an extra freshness. But make sure they come from an pesticide-free enviourment, as you don’t want the beans to absorb the poison.
You start by boiling the water with salt. I use about 7l per 0.5 kg of beans. Always leave the lid on! This is an obvious tip but it shortens the time to boiling a lot.
Meanwhile clean your beans. Cut of their stem and the small strings that go along the middle part. If necessary, cut them in smaller pieces.
When the water finally starts to boil add in your spices and then the beans. Lower a little bit the heat of your stove. The time of cooking is about 10min but the colour is what really matters. The beans will first turn into a bright vivid green. When they start to go pail again you have to take them about because that means they are overcooking.
Take the beans out of the boiling water and immediately rinse them with cold water so they keep their bright colour.
If needed season them with salt or sesame seeds and your beans are ready to be served.