Fill a 6-quart pot with 2 quarts water, add the shellfish-boil seasoning, and bring to boil over high heat. Turn off heat, add shrimp and cook for 1 to 2 minutes, until shrimp are pink-orange and slightly firm. Transfer shrimp to a colander and rinse under cold water.

Return the shrimp water to a boil, then reduce heat to low and gently add eggs. Simmer eggs for 14 minutes. Meanwhile, peel and chop the cooked shrimp and place in a large bowl. Transfer eggs to a strainer; rinse under cold water until cool.

Cook bacon in a skillet over medium-high heat until golden brown. Transfer to a small bowl and crumble. Peel eggs; cut in half lengthwise. Separate the whites from the yolks; coarsely chop the egg whites and add to the bowl with the chopped shrimp.

Press the yolks through a mesh strainer and into a large bowl. Add mayonnaise, Tabasco, mustard, and 1 tsp. salt; whisk until mixture is consistency of cake batter, about 1 minute. Fold yolk mixture into shrimp mixture, add bacon and green onion; toss. Season with salt and pepper; toss.

Use 1 cup per sandwich, along with sliced tomatoes and lettuce. Serve immediately.