Step 1
Bring a large pot of lightly salted water to a boil. Add the pasta, and cook until tender, about 8 minutes. Drain, and rinse under cold water to cool.
Step 2
Meanwhile, cook the bacon in a large deep skillet over medium-high heat until browned and crisp. Remove from the pan and drain on paper towels.
Step 3
Stir the Ranch dressing, onion, and tomatoes together in a large bowl. Mix them in the cooled pasta. Let The pasta suck in some of the dressing. Refrigerate for a few hours or overnight. Crumble bacon over the top just before serving.
