1 package Hidden Valley Ranch Dressing Mix (or 3 Tbsp. if you buy it in the canister like I do!)
For the dressing/sauce:
Mix all ingredients together and let it chill for a bit to thicken up. The "normal" ranch dressing doesn't have the sour cream in it, but when you add the sour cream, the dressing is thicker and creamier and a little tangy. It also holds onto the pasta better, which is a good thing!
To put it all together, in a large bowl, add in all the ingredients (tomatoes, bacon, pasta, salt & pepper), then pour about 2 cups of the of the Ranch dressing over the top. Toss and coat all ingredients until you have a creamy pasta salad.
If you're preparing this ahead of time, you can add the dressing, salt, and pepper to the pasta salad and let it chill for a few hours or overnight, but always save the bacon and tomatoes and mix them in right before serving (so they stay crisp and don't get soggy). You can have them all cooked, diced, etc. and ready to go...just don't add them in yet!
You may need to add more Ranch if you let it chill first (the pasta seems to absorb the dressing the longer it sits), but does anyone object to extra Ranch dressing? Not me!!