Carefully remove the side string from the beans as well as cut their ends.

Place a large sauté pan on medium-high heat. Add the butter and wait for a minute or two melt and froth.

Add the beans and spread them all over the pans so that each one of them is touching the pan. Let cook for 2-3 minutes until they blister and char and turn them to their other side to do the same for about 1 ½ minutes.

Pour the Soy sauce, toss and serve.