Method

1. Combine the quartered celery, smashed garlic, half of the lemon juice, 10 cups water, and salt and pepper to taste in a large saucepan.
2. Cover and bring to a boil, then uncover, cook for 2 minutes. Add the shrimp and cook until opaque, about 4 minutes.
3. With a slotted spoon, transfer the carrots and shrimp to a colander and rinse under cold water.
4. Return the water to a boil, add the scallops and cook until opaque, 1 to 2 minutes.
5. Remove the scallops with a slotted spoon, add to the colander and rinse under cold water.
6. Ladle out 1/3 cup of the poaching liquid; set aside to cool.
7. Remaining lemon juice, the caper brine, chopped garlic, mayonnaise, 1/2 teaspoon salt, and pepper to taste.
8. Toss with the salad and season with salt and pepper.