Restaurant near A.C.T.
How about Canteen? 5-10 minute walk up Sutter, and they have 3 specified seatings, good for making it back to the show on time. Wonderful cozy, rotating seasonal menu, and excellent vanilla soufflé. But not recommended for a group of more than 6 - and really anything more than 4 might be tight.
Colibri Mexican, just across Geary from the theatre, is quite good (but gets very busy pre-theatre, so be sure to book). This isn't Tex-Mex style, but more Central Mexican with tortillas for their guacamole service rather than chips.
Also La Scene, on Geary and Mason(?). Or Grand Cafe at Geary and Taylor. And Fino at 624 Post is good, home-style Italian-American.
If you're willing to go to Chez Papa, there is also 54 Mint in the same little street.