Στο σάντουιτς βάζω λίγη μουστάρδα και λίγη μαγιονέζα, αλλά όχι πολύ.

Στο is the contraction of σε + το.

• σε = in, into, on, at depending on context
• το = the for a neuter singular noun

So:

• το σάντουιτς = the sandwich
• στο σάντουιτς = in/on the sandwich

With food, English often says in the sandwich or on the sandwich, while Greek commonly uses σε here.

Also, σάντουιτς is treated as a neuter noun, so it takes το.

Σάντουιτς is a borrowed word, and in Modern Greek borrowed food/item words like this are very often treated as neuter.

So you get:

• το σάντουιτς = the sandwich
• στο σάντουιτς = in/on the sandwich
• τα σάντουιτς = the sandwiches

The noun itself usually stays the same, and the article shows its gender, number, and case.

Βάζω means I put / I add / I put on.

Greek present tense can be used for:

• something happening right now
• a habitual action
• a general statement about what someone does

So in this sentence, βάζω can mean:

• I put
• I usually put
• I add

In food contexts, βάζω is very common for adding ingredients or condiments.

Because λίγη agrees with the nouns it describes.

Both nouns are feminine singular:

• η μουστάρδα = the mustard
• η μαγιονέζα = the mayonnaise

So the form must also be feminine singular:

• λίγη μουστάρδα
• λίγη μαγιονέζα

Compare:

• λίγος = masculine
• λίγη = feminine
• λίγο = neuter

Here, λίγη means a little / some.

In Greek, nouns have grammatical gender, and these two are simply learned as feminine nouns:

• η μουστάρδα
• η μαγιονέζα

That is why any adjective or quantifier describing them must also be feminine:

• λίγη μουστάρδα
• λίγη μαγιονέζα

This is grammatical gender, not biological gender.

Because the speaker is talking about some amount of mustard and mayonnaise, not about a specific, already-identified mustard or mayonnaise.

So Greek naturally says:

• λίγη μουστάρδα = a little mustard
• λίγη μαγιονέζα = a little mayonnaise

This is similar to English mass nouns, where you often do not use the unless you mean something specific.

If you said τη μουστάρδα or τη μαγιονέζα, it would usually sound more specific, like the mustard or the mayonnaise already known in context.

In this sentence, repeating λίγη is the most natural and clear way:

• λίγη μουστάρδα και λίγη μαγιονέζα

It shows that each item gets a little.

You may sometimes hear one modifier covering two nouns, but with food items like this, Greek very often repeats the word. It sounds balanced and natural.

So repeating λίγη is not unnecessary—it is standard Greek style here.

This is a very common learner question.

Here, πολύ is being used adverbially, meaning:

• but not much
• but not too much

When πολύ is used as an adverb, it stays πολύ.

Compare:

• λίγη μουστάρδα, αλλά όχι πολύ = a little mustard, but not much
• όχι πολλή μουστάρδα = not a lot of mustard

In the second example, πολλή directly describes the feminine noun μουστάρδα, so it agrees with it.

In your sentence, όχι πολύ means something more like not too much overall, so the adverb form is used.

Here it means much / too much, not very.

Πολύ can mean different things depending on use:

• as an adverb: very
  • πολύ καλό = very good
• with quantity: much / a lot
  • όχι πολύ = not much / not too much

In this sentence, it refers to quantity, because we are talking about how much mustard and mayonnaise is added.

They are basic connectors:

• και = and
• αλλά = but

So the structure is:

• λίγη μουστάρδα και λίγη μαγιονέζα = a little mustard and a little mayonnaise
• αλλά όχι πολύ = but not much / but not too much

This is a very common Greek sentence pattern:

• statement
• then a contrast introduced by αλλά

The given order is very natural:

• Στο σάντουιτς βάζω λίγη μουστάρδα και λίγη μαγιονέζα, αλλά όχι πολύ.

Greek word order is more flexible than English, but this version sounds neutral and normal.

Other orders are possible for emphasis, for example:

• Βάζω λίγη μουστάρδα και λίγη μαγιονέζα στο σάντουιτς...
• Λίγη μουστάρδα και λίγη μαγιονέζα βάζω στο σάντουιτς...

But the original sentence is the best choice for a straightforward statement.

In practice, it can cover the idea of in/on the sandwich, depending on how English would naturally express it.

Greek often uses σε in food contexts where English might choose either preposition. So you do not need to force a strict distinction every time.

For a learner, the important idea is:

• βάζω κάτι στο σάντουιτς = I put/add something in/on the sandwich

That is the natural Greek phrasing.