Η αδερφή μου τρώει μανιτάρια με χοιρινό, ενώ εγώ προτιμώ μοσχάρι με ρύζι.

That is normal in Greek.

Greek usually uses the definite article with family words and possessives:

• η αδερφή μου = my sister
• ο αδερφός μου = my brother
• η μητέρα μου = my mother

So although it looks like the sister my word-for-word, the natural English translation is simply my sister.

In Greek, weak possessive forms like μου often come after the noun:

• η αδερφή μου = my sister
• το σπίτι μου = my house
• οι φίλοι μου = my friends

So the usual pattern is:

• article + noun + possessive

This is one of the most common basic Greek structures.

Both exist.

• αδερφή is very common in everyday Modern Greek
• αδελφή is a more formal or older-style variant

A learner will hear αδερφή very often in normal speech.

Τρώει is the 3rd person singular form of the verb τρώω = to eat.

So:

• τρώω = I eat
• τρώς = you eat
• τρώει = he/she/it eats

Since η αδερφή μου is she, the verb must be τρώει.

Προτιμώ is the 1st person singular form of προτιμώ = to prefer.

So:

• προτιμώ = I prefer
• προτιμάς = you prefer
• προτιμά = he/she prefers

Greek verbs change form depending on the subject, just like I am / she is in English, but usually more systematically.

Because εγώ adds emphasis or contrast.

Greek often leaves subject pronouns out, because the verb ending already shows the person. So just προτιμώ can mean I prefer.

But here the sentence contrasts two people:

• Η αδερφή μου...
• ενώ εγώ...

So εγώ is used for emphasis, like:

• whereas I prefer...
• but I prefer...

It helps highlight the contrast between my sister and me.

Here ενώ means something like:

• while
• whereas

It connects two contrasting ideas:

• My sister eats mushrooms with pork
• whereas I prefer beef with rice

So it is not mainly about time here. It is more about contrast.

Because Greek often omits the article when talking about food in a general or indefinite way.

So:

• τρώει μανιτάρια = she eats mushrooms
• προτιμώ μοσχάρι = I prefer beef
• με ρύζι = with rice

If you added articles, the meaning could become more specific depending on context, but without articles this sounds very natural for general food descriptions.

Because Greek is talking about mushrooms as a food item in the plural.

• μανιτάρι = mushroom
• μανιτάρια = mushrooms

This is very natural, just like English often says mushrooms rather than mushroom in food descriptions.

Με here means with.

So:

• μανιτάρια με χοιρινό = mushrooms with pork
• μοσχάρι με ρύζι = beef with rice

It links foods together in the sense of served with, cooked with, or combined with.

In practical meaning, it goes with the food phrase:

• μανιτάρια με χοιρινό = mushrooms with pork

So the sister is eating that dish or combination.

Grammatically, Greek often builds food expressions this way:

• X με Y = X with Y

Yes, historically it comes from an adjective related to pork, but in everyday Greek it is very commonly used by itself as a noun meaning pork.

So:

• χοιρινό = pork
• κοτόπουλο = chicken
• μοσχάρι = beef / veal

Greek often uses neuter forms like this for meats and foods.

It can depend on context.

Literally, μοσχάρι originally refers to a calf, so in food contexts it can mean:

• veal
• beef

In everyday translations for a sentence like this, beef is often the simplest choice, but context could make veal more accurate.

Because ενώ introduces a new clause, and Greek normally separates that with a comma.

So the sentence has two parts:

• Η αδερφή μου τρώει μανιτάρια με χοιρινό
• ενώ εγώ προτιμώ μοσχάρι με ρύζι

The comma helps show the contrast clearly.

Yes, Greek word order is more flexible than English, though not completely free.

This sentence uses a very natural order:

• Η αδερφή μου τρώει...
• ενώ εγώ προτιμώ...

But Greek can move words around for emphasis. For example, εγώ is placed where it clearly contrasts with η αδερφή μου.

So Greek word order is often shaped by:

• emphasis
• contrast
• rhythm
• style

not just strict subject-verb-object order.