После прогулки мне захотелось не мяса, а тёплого супа из чечевицы.

Because захотеться is often used as an impersonal verb meaning something like to feel like or to suddenly want. In that pattern, the person who experiences the desire goes into the dative case, so мне means to me.

So:

• Я захотел суп = I wanted soup
• Мне захотелось супа = I suddenly felt like some soup

The second version often sounds more natural when talking about a spontaneous craving or urge.

The difference is mainly aspect and the feeling it gives.

• хотелось = wanted / felt like, more like an ongoing state
• захотелось = suddenly wanted / came to feel like, focusing on the moment the desire appeared

In this sentence, После прогулки мне захотелось... suggests that after the walk, the desire arose at that point.

So захотелось is a very natural choice here because it highlights the new craving.

Because this is an impersonal construction. There is no grammatical subject like я controlling the verb.

In Russian, impersonal past-tense verbs are usually put in the neuter singular form:

• мне хотелось
• мне захотелось
• ему не спалось
• нам повезло

So захотелось is neuter singular not because anything is neuter, but because the sentence is grammatically impersonal.

With хотеться / захотеться, Russian often uses the genitive for the thing desired, especially with food, drink, and other things thought of as an indefinite amount.

So:

• мне хочется чаю
• мне захотелось супа
• мне не хочется мяса

This often gives a sense like some tea, some soup, meat as food, rather than one specific item.

In this sentence, не мяса, а тёплого супа sounds very natural because both nouns are being presented as kinds of food desired after the walk.

No. The negative part is not the whole reason, because the positive part is also genitive: тёплого супа.

The main reason is the construction with захотелось, which commonly allows or prefers the genitive in this kind of context. The не ... а ... contrast then keeps both items in the same case:

• не мяса, а супа

So the genitive is part of the overall structure, not just a result of negation.

Because adjectives in Russian must agree with the noun they describe in case, number, and gender.

Here:

• супа is genitive singular
• so тёплый becomes тёплого to match it

That is why you get:

• тёплого супа

It means not ..., but ... in the sense of correcting or replacing one option with another.

So:

• не мяса, а тёплого супа = not meat, but warm lentil soup

This is stronger and more precise than just using но. Russian uses не X, а Y when the speaker is explicitly contrasting two alternatives and saying the first one is not the right choice.

Because а is a coordinating conjunction, and in this corrective contrast pattern Russian normally uses a comma:

• не мяса, а тёплого супа

This is standard punctuation with не ..., а ....

The preposition после takes the genitive case, so:

• прогулка → прогулки

That is why you get:

• после прогулки = after the walk / after a walk

This is just the normal case government of после.

Из means from / out of, and it takes the genitive case, so:

• чечевица → чечевицы

In food descriptions, суп из чечевицы means soup made from lentils, or simply lentil soup.

So тёплого супа из чечевицы is literally warm soup from lentils, but naturally in English you would say warm lentil soup.

Yes. Both are possible:

• чечевичный суп = lentil soup
• суп из чечевицы = soup made from lentils

The adjective form is often a bit more compact and dictionary-like, while суп из чечевицы can sound slightly more descriptive. In this sentence, супа из чечевицы sounds completely natural.

Yes, that would also be grammatical, but the nuance changes a little.

• я захотел sounds more direct: I wanted
• мне захотелось sounds more like a spontaneous craving: I felt like

Also, with я захотел, the accusative forms мясо and суп are natural. With мне захотелось, the genitive мяса / супа is especially idiomatic in this food-craving context.

So the original sentence sounds very natural if the idea is: after the walk, I found myself wanting warm lentil soup rather than meat.

Russian word order is flexible, and putting После прогулки first sets the scene right away. It answers when? before giving the main point.

So the sentence is structured roughly like this:

• After the walk → time/background
• to me there arose a desire → the feeling
• not for meat, but for warm lentil soup → what was desired

This word order is very natural because it moves from context to the main message.