It might happen that during your stay in Stockholm, you've had enough köttbullar (you can get the best ones - in my humble opinion - at Tradition by the way) or salmon. Then: go eat at Cong! It's a vietnamese streetkitchenrestaurant in Gamla stan and it is really good! It is sometimes a bit suspicious when the reviews on Google Maps are all brilliant (4.9 out of 5 with more than 200 reviews) but I can confirm that it's all well deserved. Cong is a rather small but modern place with a few tables outside. On the menu there is food that you can share on the table (or take as a starter) and some maindishes. It's all good quality, for example you get real calamares that taste like it (not the thin bits you get on most places) and the ingredients in the summerroll and the rice noodles-dish seemed fresh too, portions are generous. They have one good housewine in every colour, some beers, some soft drinks and their very delicious homemade lemonade. The staff is very friendly and helpful and does everything to make you feel welcome. Cong is open everyday and you can check out the menu here. So definitely go there and give it a try!
(And as for everything on this page: It's my personal opinion, nothing is sponsored. I just like when things are done with passion and that's when I write about it here)