Najpierw rozgrzewam olej, a dopiero potem wrzucam cebulę i warzywa.

In Polish, recipes and step-by-step instructions often use the present tense to describe what the speaker does next. It works a lot like English recipe style: I heat the oil, then I add the onion...

So rozgrzewam = I am heating / I heat
and wrzucam = I throw in / I add

This is very natural in Polish when describing a process.

If you wanted a future meaning, you would normally use perfective future forms, for example:

• rozgrzeję
• wrzucę

But in instructions, the present tense is extremely common.

Because Polish usually does not need subject pronouns when the verb ending already shows who is doing the action.

• rozgrzewam = I heat
• wrzucam = I throw in / add

The ending -am already tells you it is 1st person singular: I.

You could say Ja najpierw rozgrzewam olej..., but that would usually add emphasis, like I do it this way.

Najpierw means first or at first.
Potem means then, afterward, or later.

So the sentence is structured like:

• najpierw = first
• potem = then

This is a very common pairing in Polish when describing sequence:

• Najpierw... potem...
• First... then...

Dopiero adds emphasis and means something like:

• only then
• not until then
• only after that

So a dopiero potem is stronger than just a potem.

Compare:

• a potem wrzucam cebulę = and then I add the onion
• a dopiero potem wrzucam cebulę = and only then do I add the onion

It suggests the order is important: the oil must be heated first, and only after that should the onion and vegetables go in.

In Polish, a often links two parts of a sentence with a slight contrast or a clear step-by-step shift. It is very common in this kind of sequencing.

Here:

• Najpierw rozgrzewam olej, a dopiero potem wrzucam...

This feels like:

• First I heat the oil, and then only after that I add...

If you used i, it would sound more like simple addition:

• ...i potem wrzucam...

That is not wrong in many contexts, but a is very natural here because it separates the two stages clearly.

Because olej is the direct object of rozgrzewam, so it is in the accusative case.

The noun olej is:

• masculine
• inanimate

For many masculine inanimate nouns in Polish, the accusative singular looks exactly the same as the nominative singular.

So:

• nominative: olej
• accusative: olej

That is why you do not see a change here.

Both are direct objects after wrzucam, so both are in the accusative case, but they belong to different noun types.

cebula

This is a feminine singular noun.

• nominative: cebula
• accusative: cebulę

That is why the ending changes from -a to -ę.

warzywa

This is a neuter plural noun.

• nominative plural: warzywa
• accusative plural: warzywa

For neuter plural nouns, nominative and accusative are often the same.

So:

• wrzucam cebulę = I add the onion
• wrzucam warzywa = I add the vegetables

Wrzucam literally means something like I throw in or I toss in. In cooking, it often means put in or add, especially when you are putting ingredients into a pan or pot.

So in this sentence, wrzucam is natural and a bit vivid: you heat the oil, then you throw in / add the onion and vegetables.

Dodaję is also common in cooking and means I add. It is slightly more neutral.

So:

• wrzucam cebulę = I throw in / put in the onion
• dodaję cebulę = I add the onion

Both can work, but wrzucam feels more physical and immediate.

They are imperfective because the speaker is describing the process as it happens, step by step.

• rozgrzewać = imperfective
• wrzucać = imperfective

In instructional or narrative present, imperfective verbs are very common because they present actions as part of an ongoing sequence.

The perfective equivalents would be:

• rozgrzać → rozgrzeję
• wrzucić → wrzucę

Those forms would sound more like a completed future action:

• Najpierw rozgrzeję olej, a dopiero potem wrzucę cebulę i warzywa.

That is also grammatical, but it feels more like what I will do, whereas the original sounds like what I do in my cooking process.

Yes, Polish word order is fairly flexible, but different orders change the emphasis.

The original:

• Najpierw rozgrzewam olej, a dopiero potem wrzucam cebulę i warzywa.

This is very natural because it highlights the sequence clearly:

1. first
2. only then

You could also hear:

• Najpierw rozgrzewam olej, a potem dopiero wrzucam cebulę i warzywa.

That is possible, but a dopiero potem is usually the more natural order when you want to emphasize only afterward.

So yes, word order can move around, but the original is a strong, idiomatic version.

No. Potem is an adverb, not a preposition, so it does not govern a case.

It simply means then / afterward and modifies the whole action.

So in:

• dopiero potem wrzucam...

potem is just telling you when the action happens in relation to the previous step.

Because in Polish, coordinating conjunctions like a normally introduce a new clause, and clauses are separated by a comma.

Here you have two clauses:

• Najpierw rozgrzewam olej
• a dopiero potem wrzucam cebulę i warzywa

Each clause has its own verb:

• rozgrzewam
• wrzucam

That is why the comma is needed.

Yes, very common. It is a standard way to emphasize correct order.

It means:

• First..., and only then...
• First..., and not until after that...

You can use it in many everyday contexts, not just cooking:

• Najpierw odrabiam pracę domową, a dopiero potem oglądam film.
• First I do my homework, and only then do I watch a movie.

So this sentence teaches a very useful real-life structure.