The best lobster soup (actually, best any soup) I ever had was at Saegriffin, which appears to be either just off the map (bottom left) or not marked, and I also found the incredible hot dog hut.

So our food experience was good, but agree - the experience was incredible. Without a doubt the best day of my travels anywhere in the world was our Golden Circle tour from Reykjavik - 6 friends, great tour guide, drinking chilled vodka in a hot spring while it snowed on us.