Primer has de barrejar la ceba amb el tomàquet.

Here primer means first or first of all.

In this sentence, it is being used adverbially, not as an adjective modifying a noun, so it does not agree with anything. That is why you see primer, not primera.

Compare:

• Primer, has de barrejar... = First, you have to mix...
• la primera vegada = the first time
  Here primera agrees with the feminine noun vegada.

So in your sentence, primer is just marking the first step.

Has de barrejar is the structure haver de + infinitive, which means to have to do something or must.

Breaking it down:

• has = you have (from haver, for tu)
• de = part of the structure
• barrejar = to mix

So:

• has de barrejar = you have to mix

This is a very common way to express obligation or instructions in Catalan.

Both are possible, but they feel slightly different.

• Barreja la ceba amb el tomàquet. = a direct command: Mix the onion with the tomato.
• Has de barrejar la ceba amb el tomàquet. = You have to mix the onion with the tomato, which sounds more like an instruction or requirement.

In recipes, manuals, and step-by-step explanations, Catalan often uses both styles. The version with has de can feel a little more explanatory and less direct than the imperative.

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

Here, has already tells you the subject is tu:

• (Tu) has de barrejar...

So tu is unnecessary unless you want emphasis or contrast.

For example:

• Tu has de barrejar la ceba, no ell. = You have to mix the onion, not him.

Without emphasis, Catalan usually omits the pronoun.

In this sentence, de is not being translated word-for-word as of. It is simply part of the fixed verbal construction haver de + infinitive.

So you should learn the whole pattern together:

• he de
• has de
• ha de
• hem de
• heu de
• han de

Examples:

• He de marxar. = I have to leave.
• Han de venir. = They have to come.

So in your sentence, de is there because Catalan requires it in this structure.

Catalan uses definite articles much more often than English, especially with nouns that refer to specific ingredients, things already understood in context, or general items in instructions.

So in a recipe step, Catalan naturally says:

• la ceba
• el tomàquet

where English might say:

• onion
• tomato

This does not necessarily mean a very specific onion or tomato in a strong sense; it is just normal Catalan usage.

Because ceba is feminine and tomàquet is masculine.

So the articles have to agree:

• la ceba = feminine singular
• el tomàquet = masculine singular

This is something you simply have to learn with the noun. In Catalan, noun gender is important because articles and some adjectives must match it.

Amb means with.

So:

• barrejar la ceba amb el tomàquet = to mix the onion with the tomato

You would not normally use i here, because i means and, not with.

Compare:

• ceba i tomàquet = onion and tomato
  This just names two items.
• barrejar la ceba amb el tomàquet = mix the onion with the tomato
  This expresses the action of combining them.

Yes. You could also say:

• Primer has de barrejar el tomàquet amb la ceba.

That is grammatically fine. The basic meaning stays the same.

The order may depend on:

• which ingredient was mentioned first before
• which one the speaker wants to highlight
• the natural flow of the recipe

So the original order is not the only possible one.

Yes, although the beginning is the most natural place when listing steps.

Common options include:

• Primer has de barrejar la ceba amb el tomàquet.
• Has de barrejar primer la ceba amb el tomàquet.

The first version is usually better for recipe-style instructions because primer clearly introduces step one.

Putting primer later can still work, but it may sound more like you are emphasizing the timing of the mixing rather than simply numbering the steps.

The accent mark in tomàquet shows where the stress falls: to-MÀ-quet.

So the stressed syllable is mà.

Accent marks in Catalan often help you know pronunciation and stress. They can also show vowel quality, depending on the dialect and the word.

A rough pronunciation guide for the whole sentence is:

pri-MER as də bə-rə-JAR lə SE-bə am əl tu-MA-kət

Exact pronunciation varies by dialect, but the key points are:

• h in has is silent
• barrejar is stressed on the last syllable
• tomàquet is stressed on mà