Iceland other than Reykjavik?
I got married (we eloped) by one of the waterfalls near Hotel Ranga in 2010. I arranged to have a 6-course menu for the two of us on our wedding night and 5-course menus on the evenings before and after the wedding. The food was fantastic, locally sourced and very creative, but heavy. 5 courses were more than enough and frankly, all 5 could have been smaller, especially were proteins were concerned. We opted for wine pairings each night and the pourings were more than generous. In all, we had a great time! I highly recommend arriving around noon, having a very light lunch, enjoying the surroundings in the afternoon, eating a later dinner, staying the night and partaking of the awesome buffet breakfast. You'll spend a pretty penny, but for a night it's worth the splurge.
If you get a chance to go to the Snaefellsnes Peninsula, I highly recommend a night or two at Hotel Budir. The food and experience were a little more subdued than at Hotel Ranga, but came a close second in quality. We stayed in a lovely room that had a bathtub right in the room. It was one of the best rooms in the house, but we called a few days in advance to book it and were offered the room at the regular rate, which was awesome. Needless to say, they weren't very busy that night (it was a weeknight in early October).
The food was great, with unusual options, in the Isafjordur area, but that's way off the ring road.
We enjoyed the Myvatn and Husavik areas, but our food experiences there didn't blow me away.
We spent 3 weeks driving around most of the island. If you want more details about some of the lesser known places, I'll dig up my guidebook and journal. I may have listed restaurant names in my journal, or else marked up my guidebook. I also may have detailed most of the meals we ate, particularly anything memorable. Look up my profile and drop me an email if you're interested. Always happy to chat about excellent trips. Iceland was otherworldly, in terms of untamed nature.