Learn German: Ich will, dass du das Filet sofort anrichtest! - I want you to plate the fillet immediately!

You would drop Ich will, dass and use werden with the infinitive to make it an indisputable command: Du wirst das Filet sofort anrichten! Notice how the separable verb anrichten is put back into its full infinitive form at the end of the sentence.

Why does the German sentence use Ich will, dass du... instead of a direct translation of 'I want you to...'?

German does not use the 'want someone to do something' construction with an infinitive. You cannot say Ich will dich anrichten. Instead, you must always use a dass (that) clause: literally, 'I want that you plate the fillet.'

Why is it anrichtest as one word at the end, instead of richtest ... an?

Because dass introduces a subordinate clause, which forces the conjugated verb to the very end of the sentence. When a separable verb like anrichten is forced to the end in a subordinate clause, its prefix (an-) and the conjugated verb (richtest) reattach and are written as a single word.

How is the word Filet pronounced in German?

It largely keeps its French pronunciation. The final 't' is silent, and the stress is on the second syllable. Like many French loanwords in German, it takes the neuter gender (das Filet).