I got this recipe from my mother-in-law several years ago. Like she said - it's really good! Especially for a cool summer meal.
While it's best with fresh vegetables, I have used canned tomatoes and frozen broccoli in this, and it turns out just fine. I always use Italian salad dressing, but it could be made with whatever kind you like, perhaps Ranch - whatever you like. It makes a lot, so I usually have to store it in a 4-quart or 5-quart ice cream bucket because I don't have any other containers big enough. Love those ice cream buckets for everything!