Jeg tilsætter salt, fordi suppen ellers smager fladt.

Tilsætter is the present tense form of the verb at tilsætte (to add). Danish verbs don’t change for person (no I add / he adds difference), but they do change for tense:

• Infinitive: (at) tilsætte
• Present: tilsætter
• Past: tilsatte
• Past participle: tilsat

That’s a normal Danish main clause with V2 (verb-second) word order: 1) Jeg (subject) 2) tilsætter (finite verb) 3) salt (object)

If you start with something else (time/place, etc.), the verb still stays second and the subject moves after the verb.

Fordi introduces a subordinate clause, and subordinate clauses generally have non-V2 word order: the finite verb does not move to position 2.

So you get:

• fordi suppen ellers smager fladt
  • subject: suppen
  • adverb: ellers
  • verb: smager
  • complement: fladt

Compare:

• Main clause style (V2): Suppen smager ellers fladt.
• Subordinate clause style: ... fordi suppen ellers smager fladt.

Ellers means otherwise / if not. In subordinate clauses it typically sits in the adverb slot, usually after the subject and before the verb:

• suppen ellers smager

So the structure is basically: because the soup otherwise tastes flat.

In Danish, it’s standard to put a comma before a subordinate clause introduced by words like fordi, at, som, etc. So:

• Jeg tilsætter salt, fordi ...

(Some writing styles have slightly different comma rules, but this comma is very common and often expected.)

Suppen is the definite form: the soup.

• suppe = soup (in general / some soup)
• suppen = the soup (a specific soup already known in context)

Danish often expresses the by using a suffix on the noun (here -en).

Here salt is used as an uncountable ingredient in a general sense: (some) salt. You typically keep it indefinite when you mean an unspecified amount.

Saltet would mean the salt, i.e., a specific salt already identified (for example, the salt on the table).

In expressions like smage + adjective, Danish commonly uses the neuter form (-t), functioning a bit like an adverbial/predicative description of the taste:

• smager godt (tastes good)
• smager sødt (tastes sweet)
• smager fladt (tastes flat/bland)

It’s an idiomatic pattern: the -t form is very common after verbs of perception like smage.

Related idea, but in this context smager fladt usually means bland / lacking depth / not flavorful enough, not literally “flat” in shape. It’s a fixed, natural collocation for taste.

Yes. These are common alternatives with slightly different feel:

• Jeg tilsætter salt ... = neutral, a bit “recipe-like”
• Jeg tilføjer salt ... = also neutral, slightly more formal
• Jeg kommer salt i (suppen) ... = very common spoken Danish (I put salt in)

The fordi-clause would stay the same.