I had my first taste of sour cream raisin pie at the Norse Nook in Osseo, WI more than 30 years ago. This place and this pie were one of about 10 restaurants excerpted from the original Roadfood book by Esquire Magazine. I believe this article did a lot to put roadfood and the Sterns on the map, so to speadk
I see that the Nook is still around, though it looks to have expanded to additional locations and become a bit "corporate." When i was there, it was a small rural diner in a tiny town.
NB: The other places mentioned in the Esquire article that I can remember are/were:
The Orange Inn (Laguna Beach, CA)
Arthur Bryant's Barbecue (Kansas City, Mo)
Louie Mueller (Taylor TX, though originally listed as in Waelder)
Ma Groover's Pig 'n Plate (Valdosta, GA)
Doe's Eat Place (Greenville, MS)
Shields Date Farm (not sure about this one)
Nunan's Lobster Hut (Kennebunkport, ME)
The Dorset Inn (not sure about this one either, but there was a Vermont diner) (Dorset, VT)
Corrections/additions welcomed. Remember, this list is from the Esquire article (August 1978)