Ni kontrolos, ĉu la saŭco bezonas ingrediencon aŭ ne.

Here ĉu introduces an indirect yes/no question. It means whether or if in the sense of whether or not.

So:

• Ĉu la saŭco bezonas ingrediencon? = a direct yes/no question
• Ni kontrolos, ĉu la saŭco bezonas ingrediencon. = We will check whether the sauce needs an ingredient.

This is one of the most common uses of ĉu.

Because Esperanto separates two different kinds of English if:

• ĉu = whether / if for a yes-no question
• se = if for a condition

So:

• Ni kontrolos, ĉu la saŭco bezonas ingrediencon. = We will check whether the sauce needs an ingredient.
• Se la saŭco bezonas ingrediencon, ni aldonos ĝin. = If the sauce needs an ingredient, we will add it.

English uses if for both ideas, but Esperanto usually does not.

Because the two verbs refer to different times:

• kontrolos = will check → the checking happens in the future
• bezonas = needs → the question is about whether the sauce needs it at that time

Esperanto does not force the second verb to match the first one just because it is in a subordinate clause. You choose the tense that matches the meaning.

So bezonas is natural if the idea is: When we check, we want to know whether it needs an ingredient.

If you said bezonos, that would suggest will need later, which is a different idea.

La is the definite article, meaning the.

So la saŭco means the sauce: a specific sauce that speaker and listener already know about, or the sauce currently being discussed.

If you said just saŭco, it would sound more like sauce in a general or less specific sense.

Because Esperanto has no indefinite article. There is a word for the (la), but no separate words for a/an.

So:

• ingredienco = an ingredient / a ingredient / ingredient
• la ingredienco = the ingredient

That means ingrediencon here naturally means an ingredient.

The -n marks the direct object. It shows what is being needed.

In this sentence:

• la saŭco = the subject, the thing doing the needing
• ingrediencon = the direct object, the thing needed

The verb bezoni is transitive, so it normally takes a direct object:

• Mi bezonas akvon. = I need water.
• La saŭco bezonas ingrediencon. = The sauce needs an ingredient.

That final -n is one of the most important grammar markers in Esperanto.

Aŭ ne means or not.

So ĉu la saŭco bezonas ingrediencon aŭ ne means whether the sauce needs an ingredient or not.

It is often used for emphasis or clarity, but it is not always necessary. You could also say:

Ni kontrolos, ĉu la saŭco bezonas ingrediencon.

That already means We will check whether the sauce needs an ingredient. Adding aŭ ne just makes the whether or not idea more explicit.

A few letters here are especially important:

• ĉ is pronounced like ch in church
• u is pronounced like oo in food
• c is pronounced like ts in cats
• ŭ is a short w-like sound used in diphthongs such as aŭ

So:

• ĉu sounds roughly like choo
• saŭco sounds roughly like SOW-tso

Also, aŭ is similar to the vowel sound in English cow.

Ŭ is not a full vowel like a, e, i, o, u. It is a short glide sound, somewhat like w, and it usually appears in diphthongs, especially:

• aŭ
• eŭ

In saŭco, the aŭ is one sound-unit, not two separate syllables. So you do not pronounce it like sa-u-co. It is one smooth sound: saŭ-co.

The comma is normal and recommended here because ĉu la saŭco bezonas ingrediencon aŭ ne is a subordinate clause.

So the structure is:

• main clause: Ni kontrolos
• subordinate clause: ĉu la saŭco bezonas ingrediencon aŭ ne

Writing the comma helps show that division clearly. In practice, you will very often see a comma before clauses introduced by words like ĉu, se, kiam, ĉar, and so on.

Yes, Esperanto word order is somewhat flexible, but the normal order here is the clearest:

Ni kontrolos, ĉu la saŭco bezonas ingrediencon aŭ ne.

Inside the subordinate clause, la saŭco is the subject and ingrediencon is the object. Because the object has -n, Esperanto can sometimes move words around more freely than English can.

Still, for a learner, the standard subject–verb–object order is best unless you have a reason to emphasize something.