Learn Farsi: کوزه‌ی خام را در کوره بگذار و به محض اینکه گرم شد، آن را در بیاور. - Put the raw pitcher in the kiln and as soon as it becomes warm, take it out.

In Farsi, when you use be mahz-e inke (as soon as) to talk about a future event, you can use the simple past tense for the action that happens first. Here, garm shod literally means 'it became warm,' but after be mahz-e inke, it translates to 'as soon as it becomes warm.' You could also use the present subjunctive (garm beshavad), but the simple past is very common in everyday Farsi to emphasize that the first action must be completely finished before the next one starts.

What is the infinitive of dar biaavar (take out) and why is the bi- in the middle of the word?

The infinitive is dar aavardan (to take out / to bring out). It is a compound verb made of the word dar and the verb aavardan (to bring). When forming the imperative (command) form, the command prefix be- (which shifts to bi- here for easier pronunciation) is placed exactly between the first part of the compound and the verb root aavar, resulting in dar biaavar.

Doesn't khaam usually mean 'raw' like raw meat? Why is it used for a pitcher?

Yes, khaam means 'raw' or 'uncooked' for food, but it is also widely used for materials that haven't been processed, refined, or fired yet. Here, a kooze-ye khaam is an unbaked clay pitcher that still needs to be fired in the kiln (koore).

Why do we use the object marker ra (or ) twice in this sentence?