Learn Hardcore Portuguese (Brazil): Qual é o seu prato favorito para o jantar?

In this question, qual is closer to which in English: you’re asking which (one) is your favorite dish among all possible dishes.
Portuguese often uses qual é before a noun like this: Qual é o seu prato favorito?
Using Que é o seu prato favorito? is not natural here; que is more common before verbs (e.g. Que você quer?) or as o que.

Why is it qual é o seu prato favorito and not qual o seu prato favorito?

Both are correct.
Qual é o seu prato favorito para o jantar? is the full form and is completely standard.
In everyday Brazilian Portuguese, people often drop é and say Qual o seu prato favorito para o jantar?; this is very common in speech and also appears in writing.

Why is it é and not está in this sentence?

É comes from ser, used for more fixed or characteristic things, like preferences, identity, nationalities, etc.
Your favorite dish is seen as a stable preference, so Portuguese uses ser: Qual é...
Using Qual está o seu prato favorito...? would be incorrect.

Why do we say o seu prato instead of just seu prato?

In Portuguese, it is very common (and usually more natural) to put a definite article before possessives: o seu prato, a sua casa, os meus amigos, etc.
You can say seu prato favorito, but in Brazil o seu prato favorito sounds a bit more natural in this kind of sentence.
So the pattern article + possessive + noun is something you should get used to.

What exactly does seu mean here? Could it also mean his/her/their?

Yes. Seu by itself can mean your, his, her, or their, depending on context.
In this sentence, because we’re clearly asking you, it is understood as your.
If there is any risk of confusion, Brazilians often prefer o prato favorito dele/dela (his/her favorite dish) instead of o seu prato favorito.

Why is it seu and not teu?

Brazilian Portuguese mainly uses você for you, and the matching possessive is seu/sua.
Teu/tua belongs to the tu system, which is less common in many regions of Brazil but frequent in some (e.g. parts of the South and Northeast).
So with você, say seu prato favorito; with tu, you would say teu prato favorito.

What does prato mean here? Is it plate or dish?

Literally, prato is plate, the object.
But in contexts about food, prato usually means dish (a prepared recipe):

Qual é o seu prato favorito? = What’s your favorite dish?
So here it clearly means dish/meal, not the physical plate.

Why is it prato favorito and not favorito prato?

In Portuguese, most adjectives usually come after the noun:

prato favorito (favorite dish)
casa bonita (beautiful house)
livro interessante (interesting book)
Putting the adjective before the noun (favorito prato) sounds wrong or, at best, very strange.

Why is favorito masculine and not favorita?

Adjectives in Portuguese agree in gender and number with the noun.
Prato is masculine singular (o prato), so the adjective must also be masculine singular: favorito.
If the noun were feminine, for example a comida, you’d say a sua comida favorita.

Why do we say para o jantar instead of para jantar?

Para o jantar uses jantar as a noun: the dinner. Literally: for the dinner.
Para jantar uses jantar more like a verb / activity: to have dinner / for having dinner.
Both can be correct, but here para o jantar emphasizes dinner as the meal/time of day, which matches the English for dinner.

What’s the difference between para o jantar and no jantar?

Para o jantar = for dinner (in the sense of suitable for / chosen for dinner).
No jantar = at dinner / during dinner (more about the moment when something happens).
So Qual é o seu prato favorito para o jantar? asks which dish you like for dinner, not what happens during dinner.

Can we drop o in para o jantar and say para jantar or para jantar?

You can say para jantar (without o) but that’s a different structure: there, jantar works more like an infinitive verb (to dine / to have dinner).
You generally cannot say para jantar if you still mean for the dinner (meal) as a noun.
So:

para o jantar = for the dinner (as a meal)
para jantar = to have dinner / for dining

Is the word order fixed, or could I say something like Qual é o seu favorito prato para o jantar?

You cannot say seu favorito prato; that order is wrong in Portuguese.
The natural order is: article + possessive + noun + adjective → o seu prato favorito.
So the sentence structure Qual é o seu prato favorito para o jantar? is the correct and natural one.

How do you pronounce qual, prato, and jantar in Brazilian Portuguese?

Approximate pronunciations:

qual → like kwow (rhymes roughly with English wow).
prato → PRAH-toh (the r is typically a strong h/kh sound in many regions, like PRAH-toh).
jantar → zhahn-TAR:
- j = zh as in measure
- an is nasal, roughly like ahn
- final r is often a soft h sound (or almost silent) in Brazil.

Is jantar a noun or a verb here? And are there other words I should know for meals?

In para o jantar, jantar is a noun meaning dinner / evening meal.
As a verb, jantar means to have dinner (e.g. Eu vou jantar às 8.).
Other common meal words:

o café da manhã – breakfast
o almoço – lunch
o jantar – dinner
(Some regions also use a janta informally for dinner, but o jantar is the standard form.)