Sebelum memasak, saya mengupas kentang lagi dan mengiris jahe pelan-pelan.

Because memasak is the verb to cook, using the meN- prefix that often marks an active verb.

• masak can mean cooked, ripe, or sometimes to cook in a more dictionary/basic sense.
• memasak is the more natural full verb form in a sentence like this.

So:

• Sebelum memasak = before cooking

This is very normal Indonesian. After sebelum, you often get a verb phrase like this without needing a subject.

Indonesian often leaves out subjects when they are understood from context.

In this sentence:

• Sebelum memasak, saya ...

it is naturally understood as Before cooking, I ...

Even though saya is not repeated inside the sebelum clause, the listener assumes the same subject unless context suggests otherwise.

So this is a common and natural structure:

• Sebelum makan, saya cuci tangan. = Before eating, I wash my hands.

Mengupas means to peel.

It comes from the root kupas = peel / remove the skin of something.

The prefix meN- creates an active verb, so:

• kupas → root
• mengupas → to peel

This pattern is very common in Indonesian:

• baca → membaca = to read
• iris → mengiris = to slice
• kupas → mengupas = to peel

Yes. Jahe is the object of mengiris.

The structure is:

• mengiris jahe = to slice ginger

This is a straightforward active verb + object pattern.

In the full sentence:

• saya mengupas kentang lagi dan mengiris jahe pelan-pelan
• I peel potatoes again and slice ginger slowly

Both kentang and jahe are objects of their respective verbs.

Here, lagi most naturally means again.

So:

• mengupas kentang lagi = peel the potatoes again

A learner should know that lagi can have several meanings depending on context, such as:

• again
• more
• in some structures, something like currently or in progress

But in this sentence, attached to the action, it is understood as again.

Yes, in some contexts lagi can suggest more/additional rather than strictly again.

So without context, mengupas kentang lagi could be interpreted as either:

• peel the potatoes again
• peel some more potatoes

Usually the surrounding context makes the intended meaning clear. Since the learner already has the meaning shown, you can follow that meaning, but it is good to know that lagi is sometimes a little flexible.

This is reduplication, which is very common in Indonesian.

• pelan = slow / softly
• pelan-pelan = slowly / gently

The repeated form often sounds more natural when used adverbially. It can give a sense of doing something in a gentle, gradual, or careful way.

So:

• mengiris jahe pelan-pelan = slice the ginger slowly / gently

In everyday Indonesian, pelan-pelan is extremely common.

It describes the action, not the ginger.

So:

• mengiris jahe pelan-pelan

means:

• slice the ginger slowly

not:

• the slow ginger

In Indonesian, adverbs often come after the verb or after the verb-object phrase, so this word order is normal.

Indonesian does not use articles the way English does.

There is no direct equivalent of the, a, or an in most ordinary sentences.

So:

• kentang can mean potato, potatoes, the potato, the potatoes, depending on context.
• jahe can mean ginger, the ginger, or some ginger, depending on context.

You figure it out from the situation rather than from an article.

Indonesian nouns usually do not have to show singular vs. plural.

So:

• kentang can mean potato or potatoes
• jahe can mean ginger as a mass noun, or a piece/amount of ginger depending on context

If Indonesian really needs to emphasize plural, it can use reduplication:

• kentang-kentang = potatoes

But in normal speech, people often do not mark plural if the meaning is already clear.

The comma separates the introductory time phrase from the main clause.

• Sebelum memasak, saya mengupas kentang lagi ...

This is similar to English:

• Before cooking, I peeled the potatoes again ...

In Indonesian, punctuation can be somewhat flexible in casual writing, but this comma is perfectly natural and helps readability.

Both mean I, but they differ in tone/register.

• saya = more neutral, polite, standard
• aku = more casual, personal, informal

So this sentence sounds neutral and standard because it uses saya. In conversation with close friends, aku might also be possible:

• Sebelum memasak, aku mengupas kentang lagi ...

The meaning stays the same, but the tone becomes more informal.

Indonesian verbs do not change form for tense the way English verbs do.

So mengupas, mengiris, and memasak do not themselves tell you whether the action is past, present, or future.

The time is understood from context, or from added time words such as:

• tadi = earlier
• kemarin = yesterday
• sekarang = now
• besok = tomorrow

So this sentence could mean different times in English depending on context:

• Before cooking, I peel the potatoes again and slice the ginger slowly.
• Before cooking, I peeled the potatoes again and sliced the ginger slowly.

Yes. It is very typical.

The structure is:

• Sebelum memasak = time phrase
• saya = subject
• mengupas kentang lagi = first verb phrase
• dan mengiris jahe pelan-pelan = second verb phrase

A very natural breakdown is:

• Before cooking, I peel the potatoes again and slice the ginger slowly.

Indonesian commonly uses:

• time phrase first
• then subject
• then verb + object
• then adverbs such as lagi or pelan-pelan depending on what they modify

So the sentence is grammatically very normal and idiomatic.