Boil the pasta: Bring a large pot of well-salted water to a rolling boil. Cook the pasta until just al dente, following package time.
Reserve 1/4 cup of pasta water, then drain and rinse briefly under cool water to stop the cooking. Shake off excess water.
Whisk the dressing: In a large mixing bowl, combine lemon zest, lemon juice, olive oil, garlic, Dijon, honey, 1 teaspoon salt, black pepper, and a pinch of red pepper flakes if using. Whisk until emulsified.
Taste and adjust acidity or salt as needed.
Prep the shrimp: Pat the shrimp dry and season lightly with salt and pepper. For easy cleanup, you can sauté or poach them.
Cook the shrimp (sauté method): Heat a tablespoon of olive oil in a skillet over medium-high. Add shrimp in a single layer and cook 1–2 minutes per side, just until pink and opaque.
Transfer to a plate to cool slightly.
Cook the shrimp (poach method): Bring a saucepan of lightly salted water to a bare simmer. Add shrimp and poach 2–3 minutes, until just opaque. Drain and cool.
Combine the salad: To the bowl with dressing, add the cooked pasta, shrimp, cucumber, tomatoes, red onion, capers, and dill.
Toss gently to coat. If it looks a little dry, loosen with a splash of reserved pasta water.
Rest for flavor: Let the salad sit 10–15 minutes so the pasta absorbs the dressing. Taste again and adjust with extra lemon, dill, salt, or pepper.
Garnish and serve: Finish with a sprinkle of fresh dill and an extra crack of pepper.
Serve slightly warm or chilled.