Originally Posted by Hilde

Fingers crossed you manage to grab a spot at Maaemo! A quick look at their website just now shows openings for lunch July Friday 13th, if your stay in Oslo goes beyond that date.
Maaemo is only open Wednesdays through Saturdays, while Statholdergaarden is open Mondays through Saturdays.

Galt was awarded their first Michelin star this year, and has also received good reviews Haven't dined there myself, though.
Restaurant Kontrast is also a great spot, I particularily liked the wine pairings. I remember I did find the chairs a bit uncomfortable.

Good luck