Learn Hardcore Indonesian: Saya menambahkan kuah sop ke nasi hangat.

Both come from the root tambah “to add/increase.”
Menambah = “to add more/increase” something, often without stating the target. Example: Saya menambah gula. “I add more sugar.”
Menambahkan = “to add X to Y,” highlighting the destination/beneficiary of the addition. Pattern: menambahkan X ke/pada Y.
In this sentence you name both what is added (kuah sop) and where it goes (nasi hangat), so menambahkan is the clearest choice.

What does the suffix -kan contribute in menambahkan?

-kan often makes the verb “apply to/for” a target (an applicative sense) or “cause to” do/be something.
With menambahkan X ke Y, -kan signals you’re adding X with respect to Y (not just increasing X in the abstract).
Compare:
- Saya menambah kuah. “I add more broth.” (no destination mentioned)
- Saya menambahkan kuah ke nasi. “I add broth to the rice.” (destination Y is explicit)

Could I say menambah instead: Saya menambah kuah sop ke nasi hangat?

You’ll be understood, and some speakers do say it.
However, when you specify a destination (ke/pada Y), menambahkan is stylistically preferred and more precise.

Is ke the right preposition? What about ke atas, ke dalam, pada, or kepada?

ke = “to/toward” a place/thing; fine here.
ke atas (nasi) = “onto (the rice)” if you want to emphasize the surface.
ke dalam (nasi) would imply “into” the rice (rare here unless the rice is in a container and you mean “into the bowl of rice”).
pada can replace ke in a more formal style: menambahkan kuah sop pada nasi hangat.
kepada is for people/animate recipients, not for rice, so don’t use kepada.

Could I use di instead of ke?

di marks location (“at/on/in”), not movement. Since you are adding/pouring (movement), use ke or ke atas. With a different verb you could say:
- Saya menuangkan kuah sop di atas nasi hangat. (location of the pouring result)

Is kuah sop redundant? Isn’t sop already soup?

kuah = broth/liquid/gravy; sop/sup = soup (the whole dish).
kuah sop pinpoints the liquid part of the soup, which is natural if you’re spooning just the broth onto rice. Not redundant; it’s like saying “the soup broth.”

Which spelling is right: sop or sup?

Both are understood. In everyday Indonesian, sop (e.g., sop ayam) is very common; sup also appears and may feel a bit more standard/neutral in some contexts. Use either; local habits vary.

Do I need to specify a quantity for kuah?

Not required. Indonesian has no articles, so bare nouns are fine.
To be specific, add a quantifier/measure:
- sedikit kuah sop (a little broth)
- satu sendok sayur kuah sop (a ladleful of broth)
- secukupnya kuah sop (broth as needed)

Why is it nasi hangat and not hangat nasi?

Adjectives normally follow nouns in Indonesian. So: nasi hangat (warm rice), baju baru (new clothes), air dingin (cold water).

What’s the nuance difference between hangat and panas for food?

hangat = warm/pleasantly hot (typical collocation: nasi hangat = freshly cooked, nice to eat).
panas = hot (higher temperature; can suggest “too hot to touch/eat”).
For serving rice, nasi hangat is the usual phrase.

Can I say nasi yang hangat?

Yes, yang turns “hangat” into a relative clause (“rice that is warm”). It’s used when you need that extra clause-like feel or contrast. In simple descriptions, nasi hangat is more natural.

Is the pronoun saya necessary? Could I use aku or drop it?

saya = neutral/formal; aku = informal/intimate.
In context, Indonesian often drops the subject if it’s obvious: Menambahkan kuah sop ke nasi hangat. (understood “I”)
Choose based on formality and who you’re talking to.

Are there more natural verbs when dealing with liquids like broth?

Good alternatives:
- menuangkan kuah sop ke (atas) nasi hangat = to pour broth onto rice.
- menyiram nasi hangat dengan kuah sop = to douse/splash rice with broth (common in food context).
Colloquial speech often uses tuangin (from menuangkan) or tambahin (from menambahkan): Gue tuangin/tambahin kuah sop ke nasi.

What’s happening morphologically in menambahkan? Why not metambahkan?

Root: tambah.
The prefix meN- assimilates to the following consonant. With initial “t,” the “t” drops and the prefix becomes men-: tambah → menambah.
Then add -kan: menambah + -kan → menambahkan.