In a medium bowl, combine the mayonnaise, lemon juice, mustard, celery salt, and freshly cracked black pepper, whisking until smooth. This creates a flavorful dressing base that will coat the shrimp evenly. Add the cut shrimp pieces and fresh dill, folding gently to combine without breaking apart the delicate shrimp. I like to let this mixture chill for at least 15 minutes before assembling—it allows the flavors to meld and keeps everything cool for serving.

While the shrimp salad chills, slice the tomato into thin rounds and set aside on a paper towel to absorb excess moisture. Just before assembly, thinly slice the avocado—doing this at the last minute prevents browning and ensures a creamy texture. Keep the pea shoots ready. This strategic timing ensures all fresh components are at their peak when you build the sandwiches.

Slice each croissant in half horizontally, creating top and bottom pieces. Layer the bottom halves with pea shoots first, followed by tomato slices, creating a fresh vegetable foundation. Spoon a generous portion of the shrimp salad from Step 1 onto the tomato layer, then top with the freshly sliced avocado. I always place avocado last so it stays soft and doesn't get crushed by other ingredients.

Place the croissant tops onto each sandwich and serve immediately. The combination of cool shrimp salad, creamy avocado, and buttery croissant creates a perfect textural contrast that's best enjoyed right away.