1Combine the vinegar, garlic, mustard, and oregano in a small bowl. Add the olive oil in a slow, steady stream while whisking constantly until all the oil is incorporated. Season with salt and pepper to taste. Refrigerate until ready to use.
2Bring a large pot of lightly salted water to boil on the stove top.
3In a small bowl, pour enough of the boiling water over the sun-dried tomatoes to cover. Let stand for 30 minutes to rehydrate, then drain.
4Coarsely chop the rehydrated tomatoes.
5Meanwhile, cook the tortellini in the remaining boiling water until about 12 minutes. Drain and rinse under cold water to stop the cooking.
6Trim fat off prosciutto and cut into squares.
7Combine tomatoes, tortellini, prosciutto, garlic and drained artichoke hearts. Add vinaigrette and mix well.
8Let stand 1 hour.
9Cover and refrigerate.
Note: This can be served room temperature or chilled. We have even eaten it warmed for dinner.