The Spaniard's Mini was three tenths of a second quicker than Ford's Jari-Matti Latvala, the Petter Solberg's factory Fiesta RS WRC third quickest, nine tenths of a second behind Sordo.
WRC series leader Sebastien Loeb was fourth quickest on the Strasbourg stage, 1.4 seconds off the benchmark.
Sordo said: "It's nice to come back with the fastest time. I like this surface and I like this rally. We were close to the win last year and it would be nice to try to fight like that again this time, but we have to remember this is Sebastien [Loeb's] hometown."
Running as an asphalt event, the crews drive the 2.4-mile stage as shakedown rather than qualifying - the drivers run in competitive order rather than selecting their position on the road.
The event starts with a superspecial stage around the centre of Strasbourg this afternoon.