The Dutchman made the most of a puncture suffered by Bruce Lorgeré-Roux (Pujolracing) to finish ahead of Kevin Gilardoni (Oregon Team).
Schothorst now has a 39-point advantage over Gilardoni, for whom it was a first podium, after Oregon Team duo Niccolo Nalio and Albert Costa both retired.
Kelvin Snoeks was third.
“Last year I had nothing but bad luck, but this year it seems to be all smiles,” said Schothorst.
“After a good start to the race, I nearly lost it completely when my car didn’t want to restart after the refuelling stop. After that I was forced to take big risks against Kevin Gilardoni.
“75 points from a possible 75 is a dream start to the season.”