Learn Hardcore Turkish: Fırında yemek varken zaman hızlı geçiyor. - While the food is in the oven, time passes quickly.

var = there is/are, exists, available
iken = while/when (X) is So varken means “while there is (…)/when there is (…).” The negative counterpart is yokken = yok + iken (“while there isn’t/when there isn’t”).

What is the role of -da in fırında, and why is it -da (not -de or -ta)?

-da/-de/-ta/-te is the locative case suffix meaning “in/at/on.” Which form you use depends on:

Vowel harmony: last vowel back (a ı o u) → -da/-ta; front (e i ö ü) → -de/-te.
Consonant voicing: after a voiceless consonant (p ç t k f s ş h), the suffix-initial consonant devoices to -t.

In fırın, the last vowel is back (ı), and the final consonant n is voiced, so we use -da: fırında = “in the oven.” Compare: şehirde (in the city), parkta (in the park).

Can I say Yemek fırındayken zaman hızlı geçiyor instead? Is there a difference?

Yes. fırındayken = fırında + iken, with a buffer y because fırında ends with a vowel.

Fırında yemek varken… emphasizes the existence of food in the oven (“while there is food in the oven…”).
Yemek fırındayken… emphasizes the state/location of the food (“while the food is in the oven…”). Both are natural; the nuance is very slight in this context.

Why is it geçiyor (present continuous) instead of geçer (aorist) or geçti (past)?

geçiyor = “is passing (now/around this time),” suitable for a current or contextual observation.
geçer = general/habitual truth: “Time passes quickly (in general) when there’s food in the oven.”
geçti = simple past: “Time passed quickly (on that occasion).” Choose based on whether you mean a current situation, a general tendency, or a one-time past event.

Is hızlı the best word here, or should it be çabuk?

Both are correct, but for “time,” Turkish often prefers çabuk:

Zaman çabuk geçiyor sounds very idiomatic.
Zaman hızlı geçiyor is also fine; it literally emphasizes speed. You can compare with daha: Zaman daha çabuk/hızlı geçiyor (“Time passes faster/more quickly”).

Do I need to say zaman at all? Could I just say Hızlı geçiyor?

You can omit zaman if context makes the subject obvious; Turkish allows null subjects. For clarity or emphasis, many speakers keep zaman (or use vakit): Zaman/Vakit hızlı geçiyor.

Why is yemek singular? Could it be yemekler or bir yemek?

With var/yok for existence, the default is often a bare singular: yemek var = “there is food.”

yemekler var = “there are (some) foods/dishes” (emphasizes plurality).
bir yemek var = “there is a (single) dish/meal” (introduces one specific item). Your sentence uses the generic “there is food.”

Does yemek here mean “food,” “a meal,” or “to eat”?

Here it’s a noun meaning “food/dish/meal,” depending on context. Yemek can be:

Noun: yemek (food/meal/dish) — as in this sentence.
Verb (infinitive): yemek (to eat) — e.g., yemek istiyorum (“I want to eat”). Context disambiguates it.

Could I say Fırındaki yemek varken instead of Fırında yemek varken?

You can, but it slightly changes the focus:

Fırında yemek varken = “while there is food in the oven” (existence in that location).
Fırındaki yemek varken = “while the food that is in the oven [exists/is available]…” (points to that specific, identifiable food using -ki “the one in/at”). Use -ki when you’re singling out that particular food.

Can I put the varken clause after the main clause? Do I need a comma?

Yes, you can move it:

Fırında yemek varken zaman hızlı geçiyor.
Zaman hızlı geçiyor, fırında yemek varken. A comma is optional but common when the subordinate clause comes second, especially in writing.

How do I say “when there isn’t food in the oven, time passes slowly”?

Use yokken:

Fırında yemek yokken zaman yavaş/çabuk geçmiyor.
Or more symmetrical: Fırında yemek varken zaman çabuk geçiyor; yokken yavaş geçiyor.

Does varken ever imply “since” (a reason), not just “while”?

Primarily it’s temporal (“while/when there is”). In suggestions/imperatives it can feel like “since/while we have X available, let’s …”:

Varken yiyelim = “Let’s eat while there is (some).” But grammatically it’s still a time clause, not a causal conjunction.

Any pronunciation tips for the tricky letters here?

ı (dotless i) in fırında and hızlı: a back, unrounded vowel (like a relaxed ‘uh’).
ç in geçiyor: like “ch” in “church.”
Stress commonly falls near the end: fı-rın-DA, ge-çi-YOR.

Could I rephrase with olmak, like “when there is (food) in the oven”?

Yes:

Fırında yemek olduğu zaman/olduğunda zaman hızlı geçiyor. These are correct and mean “when there is food in the oven.” Varken is shorter and very natural; olduğu zaman/olduğunda can sound a bit more formal or event-like (a specific time when it occurs).