"I eat soup with a spoon."
Translation:Jag äter soppa med sked.
Exactly, that's sort of the point of this sentence. You can say it either way in Swedish, med sked or med en sked, but it's more natural to say just med sked. This is because med sked is like an adverbial – how do I eat soup? English has similar expressions in many cases, like 'by boat' or 'by train' where the instrument for doing something doesn't require an article.
Exactly!.. or maybe a very thick soup??? https://cheapbeets.files.wordpress.com/2011/01/051.jpg