I went to a number of local places and they were all about the same as this. I even went to a fish and chips place in Reykjavik expecting it to be cheaper since they certainly don't need to import fish, but it wasn't. Another tiny family-owned restaurant in Vik was the same as well. I honestly couldn't find cheaper food.
I do understand the difficulty in importing food to an isolated island with only 100k people. I'm just not sure that fully accounts for the increasingly high food prices across the board.
yeah, I've seen a lot of people saying food in Iceland is super expensive, but when I was there it was about as expensive as any American city. I think many tourists must still be going to like Subway. I was going to the local restaurants and even found an amazing noodle soup place for under $10 equivalent.