Bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente, about 8 to 10 minutes. Drain and rinse immediately under cold running water until fully cooled. Shake off excess water and set aside.

While the pasta cooks, prepare your vegetables. Dice the bell peppers, onion, and cucumber into similar-sized pieces for even bites. Grate the carrots on the large side of a box grater. If using frozen corn, thaw under warm water and drain well before adding.

Make the dressing. In a small bowl, whisk together the mayonnaise, sour cream or Greek yogurt, Dijon mustard, lemon juice, salt, and pepper until smooth and creamy. Taste and adjust seasoning before adding to the salad.

In a large mixing bowl, combine the cooled pasta, ham if using, grated carrots, corn, bell peppers, red onion, and cucumber. Pour the dressing over the top and toss gently until everything is evenly coated.

Serve right away, or cover and refrigerate for at least 30 minutes to let the flavors come together. If the salad looks dry after chilling, stir in a small spoonful of mayo or a splash of lemon juice. Garnish with fresh parsley or dill before serving.