Learn Hardcore Turkish: Siz isterseniz, kahveleri ben söyleyeyim.

It’s a polite conditional opener meaning roughly “if you like/if it’s okay with you,” used to soften a suggestion. Structurally, it’s the conditional of istemek “to want/like”: ister-se-niz (aorist base + conditional -se + 2nd person plural/polite ending -niz).

Why say Siz when the ending in isterseniz already tells us “you (plural/polite)”?

You don’t need siz for grammar; the -niz already encodes it. Adding siz:

adds politeness/formality and clarity,
can create contrastive emphasis (YOU, as opposed to someone else),
is very natural in this fixed phrase.

Could I say just İsterseniz without Siz?

Yes. İsterseniz, ... is perfectly natural and common. Including Siz only adds an extra touch of politeness or emphasis.

Why is it isterseniz and not istiyorsanız?

Both are possible, but they differ in nuance:

İsterseniz (aorist + conditional) is the idiomatic, neutral way to make polite offers/suggestions.
İstiyorsanız (present progressive + conditional) feels more about a current, ongoing desire and is less idiomatic here.

Is the comma after Siz isterseniz required?

Not strictly. It’s common (and recommended in careful writing) to put a comma when a subordinate clause comes first, but in everyday writing it may be omitted.

Why is kahveleri plural and in the accusative?

Plural: it refers to multiple cups of coffee for the group.
Accusative (-i): the direct object is definite/specific (the coffees already chosen/discussed). In Turkish, definite direct objects take accusative.

Could I use kahveyi, kahve, or kahveler instead of kahveleri?

Yes, with different meanings:

kahveyi: one specific coffee (singular, definite).
kahveleri: the specific coffees (plural, definite) — what you have here.
kahve (no -i): indefinite “coffee” in general (“I’ll order coffee”), typical when the object isn’t specific.
kahveler (plural, no -i): as an indefinite object it’s usually avoided; Turkish prefers singular for indefinite direct objects, so kahve söyleyeyim is more natural than kahveler söyleyeyim.

What does söylemek mean here? Isn’t it “to say/tell”?

Colloquially in restaurants/cafés, söylemek means “to order.” So kahve söylemek = “to order coffee.” Synonyms/alternatives:

sipariş vermek: to place an order (more neutral/formal).
ısmarlamak: to treat/pay for (implies you’re footing the bill).
almak (“to take/get”) also appears in ordering contexts: iki kahve alalım.

What does the ending in söyleyeyim express?

It’s the 1st-person singular optative/voluntative mood (-(y)eyim/-(y)ayım): “let me (do X), I can/I’ll (do X).” It politely offers to perform the action, fitting nicely after a conditional like Siz isterseniz.

Why is it spelled söyleyeyim, not söyleyim?

The standard form is söyle-y-eyim with a buffer y to avoid a vowel clash and with -eyim. Many people say/write söyleyim in casual speech/writing, but it’s nonstandard. Use söyleyeyim in correct/neutral writing.

Why is ben explicitly stated? Turkish often drops subject pronouns.

Here ben gives contrast/focus: “I’ll be the one to order (not someone else).” Without ben, the sentence still makes sense, but it loses that “I (as opposed to others)” nuance.

Why is the word order kahveleri ben söyleyeyim instead of ben kahveleri söyleyeyim?

In Turkish, the element immediately before the verb is in focus. Compare:

Kahveleri ben söyleyeyim: focus on ben (“let ME order the coffees”), with kahveleri as the topic (“as for the coffees…”).
Ben kahveleri söyleyeyim: focus shifts toward kahveleri (“let me order THE COFFEES”), and ben is simply the subject, not especially contrasted.
Kahveleri söyleyeyim ben: afterthought/emphasis on ben, softer contrast.

Could I turn this into a question to sound even more tentative?

Yes: Siz isterseniz, kahveleri ben söyleyeyim mi? or shorter Kahveleri söyleyeyim mi? This is like “Shall I order the coffees?” and is very polite.

Is there a difference between Siz isterseniz and adding eğer (if) — Eğer isterseniz?

Eğer simply reinforces the conditional. (Eğer) isterseniz are both fine; with polite offers, İsterseniz without eğer is already very natural.

What if I’m speaking informally to one friend?

Use the singular informal form: Sen istersen, kahveleri ben söyleyeyim. Or even just İstersen, kahveleri ben söyleyeyim.

Can I use ısmarlamak here, and what would change?

You can say: Siz isterseniz, kahveleri ben ısmarlayayım. This shifts the meaning to “let me treat/pay for the coffees,” not just “let me place the order.” Use ısmarlamak when you want to emphasize paying.