Ψήνουμε στη γάστρα ώσπου να γίνει τραγανή η κόρα.

Ψήνουμε is the present tense, first person plural, of ψήνω.

In Greek recipes, this form is very common and works like instructional language: we bake / we cook. It does not have to mean a literal we. English often prefers the imperative (Bake...), but Greek very often uses first person plural for recipe steps.

Also, the object is omitted here. Greek can leave out what is being baked if the context already makes it clear.

στη is the contracted form of σε τη.

• σε = in, at, to, on
• τη = the, feminine singular accusative

So στη γάστρα literally means in the roasting dish / in the Dutch oven / in the baking vessel.

This contraction is extremely common in Modern Greek:

• στο = σε το
• στη = σε τη
• στον = σε τον

In Modern Greek, σε normally takes the accusative, even when it expresses location.

So:

• η γάστρα = nominative
• τη γάστρα = accusative

After σε, you use the accusative whether the meaning is:

• in a place
• at a place
• to a place

So στη γάστρα is completely normal Greek.

Γάστρα is a cooking vessel used for baking/roasting, often with a lid. Depending on context, English might translate it as:

• roasting pan
• covered baking dish
• Dutch oven
• roaster

The exact English word depends on what kind of cookware is meant, but grammatically the important point is that it is a feminine noun: η γάστρα.

ώσπου να means until.

It introduces a time clause and is followed by a subjunctive form with να. So:

• ώσπου να γίνει... = until it becomes...

This is very common in Greek:

• Περίμενε ώσπου να έρθει. = Wait until he comes.
• Μείνε εδώ ώσπου να τελειώσω. = Stay here until I finish.

A very close alternative is μέχρι να.

γίνει is the aorist subjunctive form of γίνομαι after να.

Here that form is used because the sentence focuses on the result or endpoint: the moment when the crust becomes crispy.

So:

• να γίνει τραγανή = to become crispy
• να γίνεται would suggest a more repeated, ongoing, or process-like sense, which is not what this recipe step wants

Also, γίνομαι means become, not be. So the sentence is about a change of state:

• first the crust is not crispy
• then it becomes crispy

The subject of γίνει is η κόρα.

Greek word order is more flexible than English, so the subject does not have to come before the verb. In this sentence, η κόρα comes after the verb and adjective:

• να γίνει τραγανή η κόρα

This sounds natural in Greek and puts focus on the result τραγανή first. English is much stricter about word order, but Greek often moves the subject later without changing the basic meaning.

Τραγανή is the feminine singular form of the adjective τραγανός.

It matches η κόρα, which is:

• feminine
• singular
• nominative

So the agreement is:

• η κόρα → feminine singular
• τραγανή → feminine singular

This happens because τραγανή is describing what the crust becomes. It is a predicate adjective, not just an adjective sitting directly before a noun.

Compare:

• η τραγανή κόρα = the crispy crust
• η κόρα γίνεται τραγανή = the crust becomes crispy

Greek uses the definite article very regularly, often more regularly than English learners expect.

Here η κόρα means the crust, and the article is natural because we are talking about the specific crust of the thing being baked. In recipe language, Greek usually does not drop the article in a case like this.

So η κόρα is the normal way to say it, not something unusually emphatic.

Yes. Μέχρι να γίνει τραγανή η κόρα is very natural and means almost the same thing.

Both ώσπου να and μέχρι να can mean until. In many contexts they are interchangeable. A learner should recognize both.

So:

• ώσπου να γίνει τραγανή η κόρα
• μέχρι να γίνει τραγανή η κόρα

are both good Greek.