Kaşar eriyince sucuklu tost daha lezzetli oluyor.

Eriyince comes from the verb erimek = to melt.

It breaks down like this:

• eri- = verb stem
• -y- = a buffer letter
• -ince = when / once / after

So eriyince means when it melts, once it melts, or after it melts.

The stem eri- ends in a vowel, and the ending -ince also begins in a vowel sound, so Turkish inserts a buffer y between them.

So:

• eri + ince would sound awkward
• Turkish makes it eriyince

This is very common in Turkish grammar.

Usually -ince means when, once, or after.

In this sentence, Kaşar eriyince... means:

• When the kaşar melts...
• Once the kaşar has melted...

It is mainly a time relationship here, not a strong if condition.

Sucuklu means with sucuk or containing sucuk.

It is formed from:

• sucuk = Turkish sausage
• -lu / -lı / -lü / -li = with / having

So:

• sucuklu tost = toast with sucuk
• literally, sucuk-containing toast

This suffix is very common:

• peynirli = with cheese
• zeytinli = with olives
• etli = with meat

Because Turkish often uses the suffix -li/-lı/-lu/-lü to mean with or containing.

So sucuklu tost is the natural way to say toast with sucuk.

If you said sucuk tost, it would sound less standard in this context. Sucuklu tost clearly shows that the toast includes sucuk as an ingredient.

Daha means more, and lezzetli means delicious or tasty.

So:

• daha lezzetli = more delicious
• in natural English: tastier

The comparison is understood from context: the sucuk toast is tastier after the cheese melts than before.

Oluyor comes from olmak, which often means to become or to be depending on context.

Here, daha lezzetli oluyor means:

• becomes tastier
• gets tastier

So the sentence is not just saying the toast is tasty, but that it turns tastier when the cheese melts.

This is a very common thing in Turkish.

Although -yor is the present continuous form, Turkish often uses it in everyday speech for:

• general observations
• repeated situations
• things that typically happen

So daha lezzetli oluyor sounds natural and conversational: it gets tastier.

Olur is also possible in some contexts, but it can sound more like a general rule, more neutral, or slightly less conversational.

Yes. The main subject is sucuklu tost.

The structure is:

• Kaşar eriyince = when the kaşar melts
• sucuklu tost = sucuk toast
• daha lezzetli oluyor = becomes tastier

So the full meaning is: when the cheese melts, the sucuk toast becomes tastier.

Because it is the subject of the -ince clause.

In Kaşar eriyince, kaşar is the thing doing the melting, so it stays in the basic form, with no case ending.

Likewise, sucuklu tost is the subject of the main clause and also appears in the basic form.

Turkish often puts time or condition information near the beginning of the sentence.

So:

• Kaşar eriyince sucuklu tost daha lezzetli oluyor.

is a very natural Turkish word order.

In English, we could also say:

• When the kaşar melts, sucuk toast gets tastier.
• Sucuk toast gets tastier when the kaşar melts.

Both are fine in English, but Turkish commonly places the when part first.

Turkish does not use articles the same way English does.

There is no direct equivalent of the or a/an in most sentences like this. So kaşar and sucuklu tost can be understood from context.

Here the sentence sounds like a general statement:

• Sucuk toast is tastier when the kaşar melts.

It is not mainly about one specific sandwich unless the context makes that clear.

By default, it sounds like a general observation:

• Sucuk toast gets tastier when the cheese melts.

Because the nouns are unmarked and the phrasing is general, it sounds like something people know or notice in general, not necessarily one single sandwich at one single moment.

Yes. That is a very natural English translation.

Depending on how closely you want to reflect the Turkish, you could also say:

• Sucuk toast gets tastier when the kaşar melts.
• Once the kaşar melts, sucuk toast becomes tastier.

All of these match the Turkish sentence well.