Bring a large pot of water to a boil. Add the bay leaves, zest and 3 tablespoons of sea salt. Add the shrimp and cook until they start to curl, about 2 minutes. With a slotted spoon, transfer the shrimp to a bowl to cool. Cut the shrimp in half lengthwise and return to the bowl.
Bring the water back to a boil and add the green beans. Cook until tender, about 5 minutes. Drain the beans and refresh them under cold water. Discard the bay leaves and lemon zest. Pat the beans dry and add them to the shrimp.
In a small bowl, whisk the olive oil with the lemon juice, parsley, marjoram, 3/4 teaspoon of salt and 1/4 teaspoon of pepper until well combined. Pour the dressing over the shrimp and green beans and toss well to coat. Transfer the salad to a large platter and serve.
The shrimp, beans and dressing can be refrigerated, separately, overnight. Toss just before serving.