My husband brought back a homemade sour cream dill sauce from Finland. It was thick, perhaps with a puréed vegetable, but I couldn't taste cucumber or the like. There is definitely some texture there. Any suggestions?
A very common fish condiment in Sweden is "dillsås", dill sauce.
You can add some mustard and lemon if the mayo is bland.
The taste is smooth and quite neutral with the dill as the lead actor.
A note on the sour cream. It can't be a thick, heavy consistency. It should be quite light and slightly uneven in texture (whisking makes it smooth). It is almost yoghurt like and contains about 10% fat. I have seen suggestions that low fat sour cream can be quite similar. I get the impression IKEA stocks it globally.
It should look something like