Om du hade hackat löken tidigare, skulle soppan redan vara färdig nu.

It is a mixed conditional.

• The if-clause talks about an unreal past action: hade hackat = had chopped
• The main clause talks about a present result: skulle ... vara färdig nu = would be ready now

So the idea is:

• something did not happen earlier in the past
• because of that, the result is different now

This is very similar to English:

• If you had chopped the onion earlier, the soup would already be ready now.

Because Swedish uses the pluperfect for an unreal past condition.

The structure is:

• hade
  • supine
• hade hackat = had chopped

In conditional sentences like this, Swedish often uses:

• Om + subject + hade + supine, for a past condition that did not happen

So:

• Om du hade hackat löken tidigare
  = If you had chopped the onion earlier

This tells us the chopping should have happened before, but in reality it did not.

Because the result is about now, not about the past.

• skulle vara färdig nu = would be ready now

If the result were also in the past, Swedish would normally use:

• skulle ha varit = would have been

Compare:

• Om du hade hackat löken tidigare, skulle soppan redan vara färdig nu.
  Past cause → present result

• Om du hade hackat löken tidigare, skulle soppan redan ha varit färdig då.
  Past cause → past result

So vara is correct here because the sentence is talking about the soup’s state at the present time.

Because Swedish follows the V2 rule in main clauses: the finite verb must come in the second position.

Here, the whole if-clause comes first:

• Om du hade hackat löken tidigare

After that, the main clause begins, and the finite verb must come first in that clause:

• skulle soppan redan vara färdig nu

So the order becomes:

• first position: the whole om-clause
• second position: skulle
• then the subject: soppan

If you started with the main clause instead, you would get:

• Soppan skulle redan vara färdig nu om du hade hackat löken tidigare.

That is also correct.

Here, hackat is the supine form of hacka.

In Swedish, after har and hade, you use the supine, not the infinitive and not the ordinary past tense.

• hacka = infinitive
• hackade = past tense
• hackat = supine

So:

• du hade hackat = you had chopped

A useful comparison:

• Du hade hackat löken = You had chopped the onion
• Löken är hackad = The onion is chopped

In the second example, hackad is a past participle used like an adjective.
So even if the forms can look similar, they do different jobs.

Because Swedish is talking about specific things:

• löken = the onion
• soppan = the soup

Swedish usually marks definiteness with an ending on the noun:

• lök → löken
• soppa → soppan

So instead of using a separate word like English the, Swedish often adds a suffix.

In this sentence, the speaker clearly means:

• the onion involved in this cooking situation
• the soup that is being made

Because that is the normal position for this kind of adverb in a clause with skulle.

In the main clause:

• skulle soppan redan vara färdig nu

the adverb redan comes before the infinitive vara.

A simple way to think about it:

• skulle = finite verb
• soppan = subject
• redan = adverb
• vara = infinitive

This placement is very natural in Swedish.

Also, redan and nu work together here:

• redan = already
• nu = now

So the idea is already now / by now.

Here färdig means ready or done.

In this sentence:

• soppan är färdig = the soup is ready

It is färdig because soppan is a singular common-gender noun.

Swedish predicate adjectives agree with the noun:

• soppan är färdig = the soup is ready
• huset är färdigt = the house is ready
• sopporna är färdiga = the soups are ready

So färdig is the correct form for soppan.

Not usually in everyday modern Swedish.

Swedish mostly expresses unreal or hypothetical meaning with:

• tense forms like hade
• modal verbs like skulle

So in this sentence, Swedish does not need a special subjunctive ending. The combination of:

• Om du hade hackat ...
• skulle soppan ...

already shows that the situation is hypothetical and contrary to fact.

There are some older or more formal subjunctive-style forms, such as vore, but they are much less central in modern Swedish than in older language.

Yes. In a more formal or slightly literary style, Swedish can omit om and use inversion instead:

• Hade du hackat löken tidigare, skulle soppan redan vara färdig nu.

This means the same thing.

So you have two correct versions:

• Om du hade hackat löken tidigare, skulle soppan redan vara färdig nu.
• Hade du hackat löken tidigare, skulle soppan redan vara färdig nu.

The version with om is usually the safest and most straightforward for learners.