I just googled it - looks like Globus delicatessa, schwarzenbach in niederdorf (you can order online), some other places. I think my husband likes the stuff from Hagen grote, though it is probably overpriced.

He‘s actually the rice dude - makes risotto, paella.

You might also look in jelmoli. In Winterthur, Markthalle Trivisano might have the rice as well.