I went to Cafe Hangmattan last summer whilst visiting Stockholm and wandering around the area.
Really liked the atmosphere of the place; alternative, relaxed, inviting. Unfortunately, they were all out of the main dishes and only had salads/sandwiches left, so I went with the owner's suggestion and it certainly didn't disappoint. Hearty portion size and really healthy and filling. The smoothie I had was awesome and the crumble for desert was heavenly. Big thumbs up.
Cons: They were all out of main dishes..., ...but my fault for arriving a bit late