Ich weiß nicht, ob sie lieber Blumenkohl oder Brokkoli essen möchte.

I do not know whether she would rather eat cauliflower or broccoli.

Breakdown of Ich weiß nicht, ob sie lieber Blumenkohl oder Brokkoli essen möchte.

• essen: to eat
• ich: I
• nicht: not
• möchten: would like to

Questions & Answers about Ich weiß nicht, ob sie lieber Blumenkohl oder Brokkoli essen möchte.

Why is ob used here?

Ob means whether / if in the sense of introducing an indirect yes/no question.

So:

• Ich weiß nicht, ob ... = I don't know whether ...

This is different from English if meaning a condition. In German:

• ob = whether
• wenn = if/when in conditional or repeated-time meanings

So in this sentence, ob is correct because the speaker does not know which option she prefers.

Why is the word order different after ob?

Because ob introduces a subordinate clause, and in German subordinate clauses the conjugated verb usually goes to the end.

Main clause:

• Ich weiß nicht
  Here weiß is in the normal second position.

Subordinate clause:

• ob sie lieber Blumenkohl oder Brokkoli essen möchte
  Here the conjugated/modal-like verb möchte goes to the end.

A useful rule:

• Main clause: verb in 2nd position
• Subordinate clause: conjugated verb at the end

Why are there two verbs at the end: essen möchte?