Cook the pasta in a large pot of salted boiling water for 8-10 minutes until al dente, then drain and rinse under cold water.

Prepare the vegetables by dicing the cucumber, halving the cherry tomatoes, and chopping the red onion.

Make the dressing by whisking mayonnaise, sour cream, lemon juice, garlic powder, dill, salt, and pepper until smooth.

Combine cooled pasta with cucumber, tomatoes, and onion, then pour dressing and toss to coat.

Chill the salad covered for at least 30 minutes to allow flavors to meld.

Serve chilled and garnish with fresh dill if desired.