Kiedy gotuję dla gości, wybieram łagodny sos, chociaż mój brat wolałby bardziej ostry.

In Polish, subject pronouns are often omitted because the verb ending already shows who is doing the action.

• gotuję = I cook / I am cooking
• wybieram = I choose / I am choosing

So ja is not necessary unless you want emphasis or contrast, for example:

• Ja wybieram łagodny sos, a on ostry.
  = I choose a mild sauce, and he chooses a spicy one.

Because the preposition dla always takes the genitive case.

The noun is:

• gość = guest
• goście = guests, in the nominative plural
• gości = guests, in the genitive plural

So after dla, you need gości:

• dla gości = for guests

This is a very common pattern in Polish: prepositions often force a specific case.

It is the direct object, so it is in the accusative case. But with a masculine inanimate noun like sos, the accusative singular looks the same as the nominative singular.

So:

• nominative: łagodny sos
• accusative: łagodny sos

That is why nothing visibly changes here.

Compare that with a feminine noun, where you would see the change:

• łagodna zupa → nominative
• wybieram łagodną zupę → accusative

Here it has a habitual meaning, so in English it is often closer to whenever.

The sentence is describing a repeated situation, not one single event:

• Kiedy gotuję dla gości...
  = When / Whenever I cook for guests...

Polish often uses the present tense like this for general habits and repeated actions.

Because Polish uses the present tense for habits, routines, and general truths, just like English often does.

So Kiedy gotuję dla gości means something like:

• When I cook for guests
• Whenever I cook for guests

It does not have to mean only right now. It can describe what usually happens.

Wolałby is the conditional form of woleć.

It is built from a past-tense-style form plus by:

• wolał = he preferred
• wolałby = he would prefer

Here it matches mój brat, which is masculine singular, so wolałby is the correct form.

Some related forms:

• wolałabym = I would prefer, said by a woman
• wolałbym = I would prefer, said by a man
• wolałaby = she would prefer

So in this sentence:

• mój brat wolałby... = my brother would prefer...

That is a very natural question, because ostrzejszy is often the more idiomatic comparative.

Polish has two main ways to make comparatives:

• synthetic comparative: ostry → ostrzejszy
• analytic comparative: bardziej ostry

Both are understandable, but for this adjective many native speakers would more naturally say ostrzejszy.

So these are both possible in meaning:

• mój brat wolałby ostrzejszy sos
• mój brat wolałby bardziej ostry sos

The version with bardziej is not impossible, but ostrzejszy is usually the more standard-sounding choice.

Because Polish often leaves out a repeated noun when it is already clear from context.

Earlier in the sentence, we already have łagodny sos, so in the second part Polish can simply say:

• bardziej ostry

with sos understood.

In English we do something similar with one:

• I choose a mild sauce, although my brother would prefer a spicier one.

In Polish, the adjective can stand on its own if the noun is obvious.

Even when sos is omitted, the adjective still has to match it in gender, number, and case.

The understood noun is:

• sos = masculine singular

And it is still the object of wolałby, so it is effectively in the accusative. For a masculine inanimate noun, the accusative singular looks the same as the nominative singular.

So:

• ostry sos → nominative
• wolałby ostry sos → accusative, but same visible form
• wolałby bardziej ostry → sos omitted, adjective remains masculine singular

Yes. In food contexts, ostry commonly means hot/spicy.

More generally, ostry can also mean things like:

• sharp
• severe
• harsh

But with sos, the food meaning is very natural.

Likewise:

• łagodny sos = mild sauce
• ostry sos = spicy sauce

You may also see pikantny, which is another common word for spicy.

Because Polish normally separates subordinate clauses with commas.

So in this sentence:

• Kiedy gotuję dla gości, ...
  The opening when-clause is followed by a comma.
• ..., chociaż mój brat wolałby bardziej ostry.
  chociaż introduces another subordinate clause, so it is also preceded by a comma.

Polish punctuation is often stricter than English in this area.

Because Polish has no articles.

So Polish does not have separate words corresponding to English a, an, or the. Whether something is definite or indefinite is understood from context.

That means:

• łagodny sos could mean a mild sauce or the mild sauce
• mój brat is clearly definite because mój already means my

Yes. Polish word order is more flexible than English word order, because case endings carry much of the grammatical information.

The given sentence sounds natural and neutral:

• Kiedy gotuję dla gości, wybieram łagodny sos, chociaż mój brat wolałby bardziej ostry.

It starts with the time clause, then gives the main statement, then adds the contrast. That is a very normal structure.

You can change word order for emphasis, but the original version is a good standard model.