Bring a large pot of salted water to a gentle boil, about 4 liters with 1 tablespoon salt, heated to 100°C (212°F).
Add the peeled and deveined shrimp to the boiling water and cook for exactly 2-3 minutes, until they turn bright pink and curl slightly. You’ll notice the flesh becoming opaque and firm.
Remove the shrimp with a slotted spoon and immediately transfer them into an ice bath to stop the cooking process and keep them tender and juicy. Let them chill for about 5 minutes.
While the shrimp cools, thinly slice the cucumber, red bell pepper, and green onions. Keep everything bite-sized and crisp for a fresh texture.
In a small bowl, whisk together the mayonnaise, freshly squeezed lemon juice, Dijon mustard, a pinch of salt, and freshly ground pepper until smooth and creamy.
Drain the chilled shrimp and gently pat them dry with paper towels to remove excess moisture. Toss the shrimp with the prepared vegetables in a large mixing bowl.
Pour the creamy dressing over the shrimp and vegetables, then gently fold everything together, ensuring an even coating without breaking the shrimp apart.
Taste the salad and adjust seasoning with more lemon juice, salt, or pepper if needed. The dressing should be tangy and vibrant, complementing the fresh ingredients.
Transfer the salad to a serving dish and sprinkle with chopped parsley or cilantro for a fresh herbal finish. Let it rest for 10 minutes at room temperature to meld the flavors.
Serve the shrimp salad chilled or at room temperature, garnished with extra herbs if desired. Enjoy the bright, crisp textures and lively flavors in every bite!