In a medium bowl, whisk together the mayonnaise, freshly squeezed lemon juice, white wine vinegar, sugar, Dijon mustard, fresh dill, salt, black pepper, and Old Bay seasoning until smooth and well combined. This dressing should taste balanced—slightly tangy from the vinegar and lemon, with subtle seafood notes from the Old Bay. Set aside while you prepare the other components. I like to taste the dressing at this point and adjust the seasoning; it should be a bit more flavorful than you want the final salad to be, since it will be diluted by the pasta and vegetables.

If the pasta isn't already cooked and cooled, boil 8 oz macaroni according to package directions until al dente, then drain and rinse thoroughly with cold water until completely cooled—this stops the cooking and prevents mushiness. While the pasta cools, prepare your vegetables: slice the green onion into thin rings, dice the bell pepper into 1/4-inch pieces, cut the celery into small 1/4-inch dice, and measure out the peas (thawed if frozen). Ensure the shrimp are cooked, tail-off, and at room temperature or chilled. Having everything prepped and ready makes assembly quick and prevents the vegetables from oxidizing.

In a large bowl, combine the cooled cooked macaroni, shrimp, green onion, bell pepper, celery, and peas. Pour the dressing from Step 1 over the mixture and toss gently but thoroughly, making sure every piece of pasta and vegetable is coated. Be careful not to break apart the shrimp while tossing. I find it helpful to use two forks or salad servers to toss gently rather than stirring, which keeps everything intact.

Transfer the dressed salad to a serving bowl or individual bowls and refrigerate for at least 30 minutes before serving. This chilling time allows the flavors to meld and makes the salad more refreshing. If making ahead, store covered in the refrigerator for up to 2 days, though it's best served within 24 hours for optimal texture.