How to Make It
In a large pot of boiling salted water, cook the beans until crisp-tender, about 5 minutes. Drain the beans in a colander and refresh under cold water. Drain and pat dry.
In a large bowl, mix the crème fraîche with the lemon zest, lemon juice, vinegar and tarragon. Season with salt and pepper. Add the lobster and green beans and toss to coat.