Bring a large pot of salted water to a boil. Add the spaghetti and cook as the label directs. Drain and rinse under cold water until cool.
Whisk the vinegar, yogurt, mustard, scallions, dill, 1/2 teaspoon salt, and pepper to taste in a large bowl. Drizzle in the olive oil, whisking to combine. Add the spaghetti, bell pepper, ham, cheese and romaine; toss to combine.
Photograph by Justin Walker
Courtesy of Food Network Magazine