Slightly moderate pricewise (by Norwegian standards that is) could be: Restaurant Eik 2. etasje in Hotel Continental, set menu at NOK 5-600, with wine pairing it'll run you approx. NOK 1,100.- Great setting, lots of buzz. Beware though, there is only the one menu.
A newcomer amongst the gastronomically ambitious is Restaurant Oscars gate, fantastic creative cuisine, meticilously prepared with attention to detail, maybe a bit too much so.. Don't eat a la carte, go for the menu with a wine pairing that actually DOES give you value for money. The full monty will set you back NOK 1,700.-