Learn Hardcore Korean: eumsigi masisseoseo dasi jumunhaesseoyo. - The food was so good that I ordered it again.

-아서/어서 is a causal connector that attaches to the verb or adjective stem to express “because.” You drop 다 from 맛있다, add 어서, forming 맛있어서 (“because it was delicious”). In Korean, this lets you link the reason clause directly to the main clause:
• 음식이 맛있어서 (reason)
• 다시 주문했어요 (result)

Why is the subject marker 이 used in 음식이 맛있어서 instead of 는?

Korean has two main particles for nouns: 이/가 marks the subject (the doer or experiencer), while 은/는 marks the topic or adds contrast. Here, you’re simply pointing out that 음식 is the thing that was delicious, so you use 이 (because 음식 ends in a consonant). If you said 음식은, you’d be setting up 음식 as the topic, implying a contrast or a known context.

Why is 다시 placed right before 주문했어요, and could I move it elsewhere?

다시 is an adverb meaning “again,” and Korean adverbs typically sit before the verb they modify. So 다시 주문했어요 means “(I) ordered again.” You could also say 음식을 다시 주문했어요, placing 다시 before the object, but you generally won’t put it after the verb.

What tense and politeness level is in 주문했어요, and what is its dictionary form?

• 주문했어요 is the polite informal past tense of 주문하다 (to order).
• Dictionary form: 주문하다
• Present polite: 주문해요
• Past polite: 주문했어요

Could I use 시키다 instead of 주문하다? What’s the difference?

Yes. In everyday speech, Koreans often say 다시 시켰어요 (“I ordered again”) using 시키다.
• 주문하다 is a bit more formal/neutral and common in writing or with delivery apps.
• 시키다 is more colloquial, often used when talking to friends or in casual settings.

Can I replace -아서/어서 with -으니까, as in 음식이 맛있으니까 다시 주문했어요?

Absolutely. -으니까 also means “because.” The nuance is very similar, but:
• -아서/어서 often states the cause as a straightforward fact.
• -으니까 can carry a slight nuance of drawing a conclusion or giving a justification.
Both are interchangeable in this sentence.

Why isn’t there a subject like 저 or 제가 (“I”) in the sentence?

Korean frequently omits subjects when they are understood from context. In this case, it’s clear the speaker is talking about themselves, so 저 or 제가 is dropped.

Why does the reason clause come before the main clause in Korean, unlike English?

Korean generally orders subordinate (dependent) clauses first, followed by the main clause. So you say 음식이 맛있어서 (reason) before 다시 주문했어요 (result). English often does the opposite or uses a conjunction like “because” mid-sentence, but Korean’s default structure is cause → effect.