Thank you.
I recommend restaurants:
Alder swiss Chuchi
Blue Monkey
Alden Restaurant
The Globus at Bellevue is a great option, especially with time constraints (though the queue can get quite long).
Japanese noodle lunch at Saki in Seefeld. A sister restaurant of Bimi Japanese restaurant.
If you like Dim Sum try the little take-away place on Walchebrücke, right by the HB and the Swiss National Museum...yes, it's take-away, but it is renowned and on a nice day you can take it into the park and enjoy in the sun
For good Thai food in my opinion, check out Chiang Mai Thai Shop (it looks like a take away place behind HB) or Roi Et (small restaurant off of Langstr.)
I think Terrasse n ear Bellevue is really good & the staff are really nice & helpful