@Katie , a few suggestions for Helsinki, if you're interested.
The strongest preferences went to
Palace, a classic restaurant with nice views.
If you are keen to trial Russian influence, then
Saslik would be a great option.
Other restaurants worth a mention that came up. They might be interesting to visit for your other meals when in town.
Elite is one of the older establishments in town but runs a modern show.
Vinkkeli is another lower key but apparently a tasty one.
Grön serves vegetarian and vegan meals. Last year I was to a similar one in Turku (2 h west of Helsinki) and it was one of the tastiest and satisfying dinners I've had in recent years. Grön was rated as the best restaurant in the country recently in a poll among hospitality professionals (though the criteria are unknown to me).
Inari, a new kid on the block and rated very well in the above poll.
You've gotten a huge variety of recommendations around the continent. Wherever you end up going, it'd be wonderful to get your comments back afterwards.