Learn Hardcore Czech: Pro mě je polévka v zimě nejlepší jídlo.

mě – normal, everyday spoken Czech
mne – more formal, literary, or emphatic
mně – never after pro; it is used after prepositions that take dative/locative (e.g. k mně, o mně)

So pro mě is the standard colloquial choice here; pro mne would also be correct, just more formal.
Pro mně is grammatically wrong.

Could I say “Pro já” instead of “Pro mě”?

No. After a preposition, Czech almost never uses the nominative form of pronouns.

já is nominative (subject form: I)
After pro, we must use the accusative → mě / mne

So:

✅ pro mě / pro mne
❌ pro já

Why does the sentence start with “Pro mě”? Is that necessary?

It is not grammatically necessary; it is word order for emphasis.

Putting Pro mě first highlights your personal opinion:

Pro mě je polévka v zimě nejlepší jídlo.
→ For me, soup is the best food in winter (personally speaking).

You could also say:

Polévka je pro mě v zimě nejlepší jídlo.
V zimě je pro mě polévka nejlepší jídlo.

All are correct; the choice mainly changes what is emphasized:

At the beginning of the sentence → strongest emphasis.
Here, you are emphasizing “for me”.

What case is “v zimě”, and why is it zimě and not zima or zimu?

V zimě uses the locative case of zima (“winter”).

The preposition v (“in”) usually takes:

locative when it means location or time inside something
- v Praze (in Prague)
- v zimě (in winter)

Declension of zima (feminine, singular):

nominative: zima (winter)
genitive: zimy
dative: zimě
accusative: zimu
locative: zimě
instrumental: zimou

So with v in the sense “in (during) winter”, we must use locative: v zimě, not v zima or v zimu.

Could I say “v zimu” or “v zimou” instead of “v zimě”?

No.

v zimu – uses accusative, wrong here
v zimou – uses instrumental, also wrong here

For time and place “in/inside” with v, you use locative:

v zimě – in winter
v létě – in summer
v noci – at night

So only v zimě is correct in this meaning.

Why is polévka in this form and not polévku or polévce?

Polévka is in the nominative singular, because it is the subject of the sentence:

Polévka je v zimě nejlepší jídlo.
→ Soup is the best food in winter.

Case summary:

Subject → nominative → polévka
Direct object → accusative → polévku (e.g. Jím polévku. – I eat soup.)
Indirect object / location etc. → other cases (polévce, etc.) depending on the preposition or verb.

Here, polévka is not an object, it’s what we are talking about, so nominative is correct.

Why is jídlo also in nominative? Shouldn’t one of them be in a different case?

With the verb být (“to be”), when you say “X is Y”, both X and Y are in the nominative:

Polévka (subj.) je nejlepší jídlo (predicate nominative).

This is similar to:

On je učitel. – He is a teacher.
(both on and učitel in nominative)

So the structure is:

[Polévka]NOM je [nejlepší jídlo]NOM.

There is no article in Czech, so jídlo can mean “a food / a dish / the food” depending on context.

How does the word “nejlepší” work here? Is it the superlative of “dobrý”?

Yes. The degrees of comparison are:

dobrý – good
lepší – better
nejlepší – best

Nejlepší is the superlative (“the best”).
It belongs to the -í adjective type (like cizí – foreign), so in nominative singular it has the same form for all genders:

nejlepší polévka (feminine) – the best soup
nejlepší jídlo (neuter) – the best food
nejlepší film (masculine inanimate) – the best film

In other cases it changes (e.g. nejlepšího, nejlepšímu), but in this sentence nominative singular is used, so it stays nejlepší.

Would it be more natural to say “Pro mě je polévka v zimě to nejlepší jídlo” with “to”?

Adding to is very common and sounds slightly more emphatic:

Pro mě je polévka v zimě nejlepší jídlo.
Pro mě je polévka v zimě to nejlepší jídlo.

Both are correct and natural. The version with to:

feels a bit more like “the best possible food”,
makes the predicate stand out: to nejlepší jídlo = that best food.

In everyday speech, many speakers actually prefer “to nejlepší jídlo” in this kind of “X is the best Y” sentence.

Are there other natural ways to express this idea, like using “mít rád”?

Yes, very natural alternatives are:

V zimě mám nejradši polévku.
→ In winter I like soup the most.
Polévka je moje nejoblíbenější jídlo v zimě.
→ Soup is my favourite food in winter.

Differences:

Pro mě je polévka v zimě nejlepší jídlo.
– a bit more objective: “for me, soup is the best food in winter.”
Mám nejradši polévku.
– clearly about personal liking (“I like it the most”).

All are correct; it’s just a stylistic choice.

Why is there no word for “the” or “a” before polévka and jídlo?

Czech has no articles (no a/an or the).

So:

polévka can mean “soup”, “a soup”, or “the soup”,
jídlo can be “food”, “a dish”, or “the food”.

The exact English translation depends on context, not on extra words in Czech.
Here, natural English is:

For me, soup is the best food in winter.

How do you pronounce “Pro mě je polévka v zimě nejlepší jídlo”?

Approximate pronunciation (slashes = phonemes, stress always on the first syllable):

Pro – /pro/
mě – /mje/ (similar to “mye”)
je – /jɛ/ (“ye”)
polévka – /ˈpolɛːfka/ (PO-layf-ka, long é)
v – /v/ (often merges with next word in fast speech)
zimě – /ˈzɪmɲɛ/ (ZIM-nye)
nejlepší – /ˈnɛjlɛpʃiː/ (NAY-lep-shee, long í)
jídlo – /ˈjiːdlɔ/ (YEE-dlo, long í)

Spoken slowly:
[Pro mě] [je] [polévka] [v zimě] [nejlepší] [jídlo].