Fill a large pot of water and place over high heat. Add a generous amount of kosher salt to season the water. The water should taste lightly seasoned but not overly salty. Trim the stem ends from the beans. When the water comes to a boil, add the green beans. Cook for 4 to 6 minutes until the beans are crisp tender.
Place a large stainless skillet over medium low heat. Add the pine nuts and sauté, stirring regularly, until the nuts are golden brown. Try not to let the skillet get too hot or the butter might burn when you add it.
When the nuts are browned, add the butter and allow to melt. Carefully add the lemon juice and zest along with the kosher salt and pepper. Bring the butter sauce to a gently simmer and then stir in the chopped tarragon. Reduce the heat and keep warm.
When the green beans are crisp tender, remove from the heat and drain through a colander. Transfer the beans to the skillet and toss in the butter sauce using tongs.
Transfer the green beans to a serving dish. Spoon any butter sauce and pine nuts remaining in the skillet over the beans. Garnish with more chopped fresh tarragon and enjoy!