I can recommend Singapore Rest near Letzigrund ? Goin there for almost 20 Years now . Laksa Is the best. Or chop stick in niederdorf . This 2 are the best and not so expensive.
In the city my favourite is Yens, especially for the sushi, is very fresh! If you want an amazing creamy curry, then go to Asiaway in Oerlikon plus price is great for Zurich!
Saigon is utterly overpriced and of low quality. The pho is small and mediocre at best and the summer rolls aren't fresh and rather pricey at 6Chf per piece!
Ban Song Thai for Thai food is highly recommended. Lunch buffet is great too. You absolutely need a reservation for dinner. Their biggest plus - no added sugar in food (sugar is actually a very common ingredient in Thai food) and hence does not spike the blood sugar like crazy. Very important for anyone monitoring their blood sugar.
I would make the effort to go to Pfaffikon Schwyz to savannaketh. Best one I've been too, most of the ones in Zurich are only ok after a few beers when your tastebuds are happy with anything... Savannaketh is five mins walk from the station. Family run.Well worth it.