Avui vull fer una sopa amb patata, ceba i tomàquet.

Avui means today, and putting it first sets the time right away: Today, I want to make...

This is very natural in Catalan. You could also say Vull fer una sopa avui, but Avui vull... sounds more like you are framing the whole sentence around today.

Vull means I want. It comes from the verb voler = to want.

This is the 1st person singular form in the present tense:

• jo vull = I want
• tu vols = you want
• ell/ella vol = he/she wants
• nosaltres volem = we want
• vosaltres voleu = you want
• ells/elles volen = they want

So Avui vull fer... literally starts as Today I want to make...

Catalan often leaves out subject pronouns when they are clear from the verb form.

So:

• vull already tells you it means I want
• jo vull is also possible, but it adds emphasis

For example:

• Avui vull fer una sopa = neutral, natural
• Avui jo vull fer una sopa = more emphatic, like I want to make a soup

This is similar to Spanish and unlike normal English, where the subject usually has to be stated.

Yes. Fer is a very common verb meaning to do or to make. In Catalan, it is normal to say fer una sopa for make a soup.

So:

• vull fer una sopa = I want to make a soup

You may also hear:

• preparar una sopa = to prepare a soup
• cuinar una sopa = to cook a soup

But fer is simple, everyday, and very idiomatic here.

Una is the feminine singular indefinite article, meaning a or one.

• una sopa = a soup

The noun sopa is feminine, so it takes una, not un.

Compare:

• una sopa
• una ceba
• una patata

If you said just vull fer sopa, that can also work in some contexts, but fer una sopa sounds like make a soup / make some soup as a specific dish.

Yes. Amb means with.

Here it introduces the ingredients:

• una sopa amb patata, ceba i tomàquet = a soup with potato, onion, and tomato

It is the normal word to use here. Very straightforward.

This is very common when listing ingredients.

In English, we often do the same thing:

• soup with potato, onion, and tomato
• or more naturally in English, with potatoes, onions, and tomatoes

In Catalan, singular nouns without articles often sound natural in ingredient lists, especially when naming the components in a general way.

So:

• amb patata, ceba i tomàquet = with potato, onion, and tomato

You could also hear other versions depending on style and context, such as:

• amb patates, cebes i tomàquets if you are thinking of actual countable items
• amb una patata, una ceba i un tomàquet if you mean exactly one of each

But in a recipe-style or ingredient-list sense, the singular bare nouns are very normal.

Yes. I means and.

So:

• patata, ceba i tomàquet = potato, onion, and tomato

A small pronunciation note: Catalan i is pronounced like ee.

Also, unlike Spanish y, Catalan i does not normally change before words beginning with an i sound. It just stays i.

Vull is usually pronounced roughly like booly without a full extra vowel at the end, though the exact sound depends on dialect.

What matters most for a learner is:

• the v in many Catalan varieties sounds close to b
• the ll is a special Catalan sound, often similar to the lli sound in million, though pronunciation varies by dialect

So vull is not pronounced like English vull would be. It is closer to bull with a palatal ll sound.

If your pronunciation is still developing, don’t worry too much at first; learners are usually understood if they say something close to bull or byool.

The accent in tomàquet shows where the stress falls.

• tomàquet is stressed on mà

So it sounds roughly like to-MA-quet.

Accent marks in Catalan are very important because they help show pronunciation and sometimes distinguish words. Here, the accent tells you not to stress the last syllable.

Yes, it sounds natural and correct.

Avui vull fer una sopa amb patata, ceba i tomàquet is a perfectly normal everyday sentence.

A speaker might also say slightly different but equally natural versions, for example:

• Avui vull preparar una sopa amb patata, ceba i tomàquet
• Avui faré una sopa amb patata, ceba i tomàquet = Today I’m going to make a soup / I’ll make a soup today

But the original sentence is simple, idiomatic, and very good Catalan.