Antes de cenar, mi abuela puso ajo y pimiento en la sartén, y luego añadió el atún.

Because antes normally takes de before a verb in the infinitive.

• antes de + infinitive → before doing something
• So antes de cenar = before eating dinner / before dinner

You also use de before a noun:

• antes de la cena = before dinner

Both are possible, but antes de cenar is very natural when talking about the action of eating dinner.

They are in the preterite because the sentence describes completed actions in sequence:

1. she put the garlic and pepper in the pan
2. then she added the tuna

That is exactly the kind of situation where Spanish uses the preterite.

• puso = preterite of poner
• añadió = preterite of añadir

If you used the imperfect instead, it would sound more like background information, repeated habit, or an action in progress.

Yes, poner basically means to put, but in cooking Spanish it can also work very naturally for putting an ingredient into something.

So puso ajo y pimiento en la sartén is a normal way to say she put those ingredients into the pan.

Other verbs are also possible, but they have slightly different feels:

• puso = put
• echó = put in / threw in / poured in
• añadió = added
• metió = put inside, inserted

In a cooking context, puso sounds completely natural.

This is a very common confusion.

• pimiento = pepper the vegetable
• pimienta = pepper the spice

So here pimiento means the vegetable, not black pepper or ground pepper.

In cooking, Spanish often uses ingredient nouns in the singular when talking about them as ingredients in a general way.

• ajo = garlic, as an ingredient
• pimiento = pepper, as an ingredient

The focus is not necessarily on the exact number of pieces. If you wanted to be more specific, you could say things like:

• dos dientes de ajo = two cloves of garlic
• un pimiento rojo = one red pepper

So the singular here is very normal.

Spanish is flexible with food and ingredient nouns, and article use can depend on how the speaker is viewing the ingredient.

Here:

• ajo y pimiento are presented as ingredients in a fairly general way
• el atún sounds like the tuna for the dish, a more identifiable ingredient

Spanish often includes the definite article with food nouns more than English does. So añadió el atún sounds very natural.

You may also hear sentences without the article in some contexts, but this version is completely standard.

Because Spanish normally uses the article with a specific, concrete object that is understood in the situation.

Here, la sartén means the pan being used for cooking.

So:

• en la sartén = in the pan

Saying en sartén would not sound natural in standard Spanish here.

The accent mark shows where the stress goes:

• sartén → stress on the last syllable

Without the accent, Spanish spelling rules would suggest a different pronunciation. The accent mark tells you the word is pronounced sar-TÉN.

The accent mark shows the stress in the preterite form:

• añadió = he/she added

It is stressed on the last syllable: a-ña-DIÓ.

This is a standard written form of the third-person singular preterite of many -iar / -adir / -ir style verbs where the ending is -ió.

For the same basic reason: it marks the stress.

• atún is pronounced a-TÚN

The accent shows that the final syllable is stressed.

Luego means then, afterwards, or later.

It helps show the order of events:

• first she put the garlic and pepper in the pan
• then she added the tuna

So it is a sequencing word, very common in narration and recipes.

Yes.

Literally, antes de cenar is before eating dinner / before having dinner because cenar is a verb.

But in natural English translation, it often comes out simply as before dinner, depending on context.

So the Spanish phrase is action-based, but the English meaning may be expressed either way.

Yes, people would understand it, but in Spain añadir is often the more natural and common choice in this kind of sentence.

• añadió = added
• agregó = added, but can sound less typical in Spain depending on context

In Spanish from Spain, añadir is especially common in recipes and cooking instructions.