Place large pot of water over medium high heat and bring to boil.
Add one tablespoon sea salt and half of one lemon to hot water.
Add one pound large shrimp and cook for 5 minutes.
Remove shrimp from water with slotted spoon. Spread out on plate and let cool for at least 15-20 minutes.
While shrimp is cooling...in a large bowl combine mayonnaise, celery, onion, thyme leaves and juice of half a lemon.
Add shrimp to bowl. Toss gently. Taste and add additional salt if needed. Refrigerate one to four hours.
Place lettuce leaves on plate. Top with chilled shrimp salad. Sprinkle with sliced fresh chives and more salt to taste. Serve chilled or at room temperature.
Notes
This is an adaptation of Ina Garten's "Tarragon Shrimp Salad". Since I don't like Tarragon, I used Thyme in it's place.