Place the beans in a large skillet and add 1/3 cup water. Heat over medium-high heat. Once the water starts boiling, cover the skillet and boil the beans for 4 minutes. Then uncover and cook until the water is fully evaporated, about 1 minute or os.
Once all the water has cooked out, add the olive oil or butter, minced shallot and kosher salt (take care because any additional moisture can cause the beans to momentarily spit). Sauté for 2 minutes more until tender, stirring frequently.
Turn off the heat and remove the beans to a bowl. Stir in the lemon juice and if using, top with grated lemon zest. Taste, then add plenty of fresh ground pepper and a few additional pinches of kosher salt. Eat immediately. Leftovers store 2 to 3 days refrigerated: though the bright green color is lost, they still taste delicious.