The phrase "hidden valley" refers to a secret or secluded area that is not easily discovered or seen by others. It implies that this valley is tucked away or concealed in some way. Full definition
I wish someone would come up with a homemade dry seasonings mix like hidden valley ranch mix. (mybakingaddiction.com)
Over 50 years ago the founder of Hidden Valley Ranch in Santa Barbara, California produced a fabulous salad dressing that is now packaged and sold in stores across the globe. (confettiandbliss.com)
For the California portion of this recipe we're incorporating a packet of Hidden Valley Ranch salad dressing and seasoning mix. (confettiandbliss.com)