I always associate beets with fish.
There's no real reason for that association outside the context of my own life: I first learned to like beets when I was living in Gentilly almost twelve years ago (wow), when I happened to be eating a lot of fish. The beets were a whim - I roasted them, rubbed the skins off, and sliced them, as a side with pan-fried fish and homemade "tartar sauce" made with pickled garlic.
The sweetness was nice with the fish, and I've gone back to it a lot of times since.
The cod fillet was smoked in the stovetop smoker after being rubbed with miso. No tartar sauce this time - just black pepper and a five-minute egg fried in cilantro oil.