Siomay itu pakai saus kacang.

In this sentence, itu comes after siomay and points to a particular siomay that is already known, visible, or previously mentioned.

So Siomay itu... can feel like:

• that siomay
• the siomay
• sometimes just a topic already under discussion

Indonesian itu is often a demonstrative (that), but after a noun it can also work a bit like English the, depending on context.

Because in Indonesian, demonstratives like ini and itu usually come after the noun they describe.

So:

• siomay itu = that/the siomay
• saus itu = that/the sauce

This is different from English, where we say that siomay.

Pakai literally means to use or to wear, but in everyday Indonesian it is also used very naturally for food to mean things like:

• use
• have
• come with
• be served with

So in Siomay itu pakai saus kacang, pakai means that the siomay is served using peanut sauce, or comes with peanut sauce.

This is a very common colloquial use of pakai.

Because pakai already carries that idea.

In English, you might say with peanut sauce, but Indonesian often uses pakai instead of a direct equivalent of with in casual speech.

Compare:

• nasi goreng pakai telur = fried rice with egg
• bakso pakai sambal = meatballs with chili sauce

You can also use dengan in some sentences, but pakai is especially common in spoken Indonesian.

Indonesian often does not need a word like English is/am/are.

In this sentence, though, the main verb is actually pakai, so the sentence is not missing a verb. It is structured more like:

• Siomay itu = the/that siomay
• pakai = uses / comes with
• saus kacang = peanut sauce

So the sentence is complete without any extra word for is.

Yes, but it changes the style.

• pakai = more common, everyday, conversational
• memakai = more formal or careful

For food, pakai sounds very natural.
Siomay itu memakai saus kacang is understandable, but it sounds more formal than people usually speak.

In normal conversation, pakai is the better choice.

Because Indonesian noun phrases usually put the main noun first and the describing word after it.

Here:

• saus = sauce
• kacang = peanut

So saus kacang literally follows the Indonesian pattern sauce peanut, but in natural English that becomes peanut sauce.

This same pattern appears in many common phrases:

• teh manis = sweet tea
• mie goreng = fried noodles
• air panas = hot water

Yes, you can, but the nuance changes a little.

• Siomay itu pakai saus kacang points to a specific siomay or a known one.
• Siomay pakai saus kacang sounds more general, like talking about siomay as a dish.

So:

• with itu = that/the siomay
• without itu = siomay in general, or a less specific statement

Both can be correct, depending on context.

Indonesian nouns usually do not change form for singular or plural.

So siomay can mean:

• one siomay
• several siomay
• siomay in general as a dish

Context tells you which one is meant.

In Siomay itu pakai saus kacang, it most naturally sounds like a specific serving or a specific siomay being referred to, but context is what makes that clear.

Yes, very natural.

Using pakai for toppings, sauces, ingredients, or extras is extremely common in everyday Indonesian. People often say things like:

• Mau pakai sambal? = Do you want chili sauce?
• Baksonya pakai mi. = The meatballs come with noodles.
• Saya pesan sate pakai lontong. = I’m ordering satay with rice cake.

So Siomay itu pakai saus kacang sounds normal and conversational.

Yes, but the structure would usually be slightly different.

You might say:

• Siomay itu disajikan dengan saus kacang. = That siomay is served with peanut sauce.

Using dengan is fine, but it often sounds a bit more formal or descriptive. In everyday speech, pakai is often shorter and more natural.

So:

• pakai saus kacang = casual, everyday
• disajikan dengan saus kacang = more formal/descriptive

Both are possible, but they are not always exactly the same in feel.

• saus kacang = peanut sauce
• bumbu kacang = peanut-based sauce/seasoning, often a little broader in meaning

For dishes like siomay, bumbu kacang is also very common and often sounds especially natural in Indonesian food contexts.

So you may hear both:

• Siomay itu pakai saus kacang.
• Siomay itu pakai bumbu kacang.

Both are understandable; bumbu kacang can feel a bit more specifically tied to Indonesian-style peanut dressing/sauce.