Για πρωινό πήρα ένα κρουασάν, ενώ η φίλη μου διάλεξε ψωμί με σαλάμι.

Literally, Για πρωινό means for breakfast.

In Greek, για often means for, and this expression is very common when talking about meals:

• Για πρωινό = for breakfast
• Για μεσημεριανό = for lunch
• Για βραδινό = for dinner

So Για πρωινό πήρα ένα κρουασάν is very naturally For breakfast, I had/got a croissant.

Because in this fixed expression, Greek normally says για πρωινό without an article.

This is similar to how languages often have set meal expressions. You will commonly see:

• για πρωινό
• για μεσημεριανό
• για βραδινό

Adding an article here would usually sound less natural unless the context is very specific.

Both are in the simple past in Greek, usually called the aorist.

• πήρα = I took / I got / I had
• διάλεξε = she chose / she picked

The aorist is used for a completed action, so here it describes what each person chose for breakfast.

Greek often uses παίρνω (to take / get) in food-ordering or food-choice contexts.

So πήρα ένα κρουασάν can mean:

• I got a croissant
• I had a croissant

It sounds natural when talking about what you chose, bought, or had as part of a meal.
If you said έφαγα ένα κρουασάν, that would mean more specifically I ate a croissant.

So:

• πήρα focuses on the choice or what you had
• έφαγα focuses on the act of eating

Because κρουασάν is a countable noun, while ψωμί here is being used as an uncountable/mass noun.

• ένα κρουασάν = one croissant
• ψωμί = bread

In this sentence, ψωμί με σαλάμι means something like bread with salami or some bread with salami, not one bread.

If you say ένα ψωμί, it often means a loaf of bread, which is a different idea.

Greek often leaves out the article when talking about food in a general or indefinite way.

So:

• ψωμί με σαλάμι = bread with salami

This sounds like naming the kind of food someone chose, rather than referring to a specific piece of bread or a specific salami.

You could add articles in other contexts, but here the article-free version is very natural.

Here ενώ means something like:

• while
• whereas
• while on the other hand

It connects the two parts of the sentence and creates a mild contrast:

• I had a croissant, while my friend chose bread with salami.

So it does not just join two actions; it also highlights the difference between the two choices.

It can do both.

1. Simultaneous actions

   • Διάβαζα ενώ εκείνη μαγείρευε.
     = I was reading while she was cooking.

2. Contrast

   • Εγώ πήρα κρουασάν, ενώ εκείνη πήρε ψωμί.
     = I got a croissant, whereas she got bread.

In your sentence, the main feeling is contrast.

Because in normal Greek, possessive pronouns like μου usually come after the noun:

• η φίλη μου = my friend
• το σπίτι μου = my house
• ο αδερφός μου = my brother

Greek also normally keeps the definite article:

• η φίλη μου, not just φίλη μου in neutral standard usage here

So the standard pattern is:

article + noun + possessive

Greek uses the definite article much more regularly than English.

So where English says simply my friend, Greek usually says:

• η φίλη μου = literally the friend my

That is the normal way to express possession with nouns in Greek.

It is in the nominative, because it is the subject of διάλεξε.

Breakdown:

• η = feminine singular nominative article
• φίλη = feminine singular nominative noun
• μου = my

So η φίλη μου διάλεξε... means my friend chose...

Because μου here is a weak possessive pronoun (a clitic). In Greek, these short possessive forms normally follow the noun:

• ο φίλος μου
• η μητέρα μου
• το βιβλίο μου

They are very common and very natural in everyday Greek.

Κρουασάν is a borrowed word, and in Greek many borrowed food words are treated as neuter, especially when they do not follow older Greek noun patterns.

That is why you get:

• ένα κρουασάν

Also, κρουασάν is typically indeclinable, meaning its form does not change across cases. The article often gives you the grammatical information.

με means with, so ψωμί με σαλάμι means bread with salami.

This is a very common way in Greek to describe food combinations:

• τοστ με τυρί = toast with cheese
• μακαρόνια με κιμά = pasta with minced meat
• ψωμί με μέλι = bread with honey

So με + food item is a basic and useful pattern.

Because σαλάμι here is being used generically as an ingredient or filling.

So:

• ψωμί με σαλάμι = bread with salami

This is similar to how English often says bread with salami, not necessarily bread with the salami.

Greek often omits the article in this kind of food-description phrase.

Yes, Greek word order is fairly flexible, although some versions sound more natural depending on emphasis.

The original sentence:

• Για πρωινό πήρα ένα κρουασάν, ενώ η φίλη μου διάλεξε ψωμί με σαλάμι.

Possible variations:

• Πήρα ένα κρουασάν για πρωινό, ενώ η φίλη μου διάλεξε ψωμί με σαλάμι.
• Η φίλη μου διάλεξε ψωμί με σαλάμι, ενώ εγώ πήρα ένα κρουασάν.

Changing the order usually changes the focus or emphasis, not the basic meaning.

Yes. Both are aorist forms, but they come from verbs that do not form the past in a completely predictable way for beginners.

• παίρνω → πήρα
• διαλέγω → διάλεξα / διάλεξε (3rd person singular)

So these are forms worth memorizing.

In particular, πήρα is very common and somewhat irregular compared with the present παίρνω.

Sometimes, depending on context, but chose/picked is the safest translation here.

• διαλέγω = choose, select, pick

If the situation is specifically ordering food in a café or restaurant, English might naturally say ordered, but the Greek verb itself mainly means chose.

Yes, it sounds natural and idiomatic.

It uses very common patterns:

• Για πρωινό...
• πήρα...
• ενώ...
• η φίλη μου...
• ψωμί με σαλάμι

A native speaker would understand it immediately, and it sounds like normal everyday Greek.