Se o molho ficar azedo, minha avó tira as sementes do tomate e começa de novo.

Here, ficar is most naturally understood as the future subjunctive.

In Portuguese, after se meaning if, when you are talking about a possible future situation, Portuguese often uses the future subjunctive:

• Se eu for... = If I go...
• Se ele tiver... = If he has...
• Se o molho ficar azedo... = If the sauce turns sour...

With many -ar verbs, the future subjunctive form looks exactly like the infinitive, so ficar can look confusing. But in this sentence, it is functioning as future subjunctive, not as a plain infinitive.

Ficar often means to become or to end up in a certain state.

So:

• ficar azedo = to become sour
• estar azedo = to be sour
• ser azedo = to be sour by nature / inherently sour

In this sentence, the idea is that the sauce was not sour before, but it turns sour. That is why ficar is the natural choice.

Because azedo agrees with o molho.

• molho is a masculine singular noun
• so the adjective must also be masculine singular: azedo

Compare:

• o molho azedo
• a sopa azeda

Adjectives in Portuguese usually agree in gender and number with the noun they describe.

The present tense here expresses a habitual action or a general reaction.

So the sentence means something like:

• Whenever the sauce turns sour, my grandmother removes the tomato seeds and starts again.

Portuguese often uses the present indicative for things someone regularly does:

• Se chove, eu fico em casa.
• Se o molho ficar azedo, minha avó tira as sementes...

It is not necessarily about one single event happening right now; it can describe what usually happens.

Tira comes from tirar, which often means:

• to take out
• to remove
• to pull out

In this sentence, minha avó tira as sementes do tomate means she removes the seeds from the tomato.

It is a very common everyday verb in Brazilian Portuguese.

Do is a contraction of:

• de + o = do

So:

• as sementes do tomate = the seeds of the tomato / the tomato’s seeds
• literally: the seeds from the tomato

This kind of contraction is extremely common in Portuguese:

• de + a = da
• em + o = no
• em + a = na

Portuguese uses definite articles more often than English does.

So as sementes literally means the seeds. In English, you might sometimes just say remove seeds, but Portuguese usually prefers the article here.

This sounds natural in Portuguese:

• tirar as sementes do tomate

Without the article, it would sound less standard in this context.

Yes, both are possible in Brazilian Portuguese:

• minha avó
• a minha avó

In Brazil, possessives can appear with or without the definite article, depending on region, style, and level of formality.

So:

• minha avó tira...
• a minha avó tira...

Both can sound natural. The version without the article is very common.

Começa de novo means starts again.

It is very close in meaning to recomeça:

• começa de novo = starts again
• recomeça = restarts / starts again

In everyday Brazilian Portuguese, começar de novo is very common and sounds natural and conversational.

In this sentence, it suggests that she abandons the spoiled attempt and begins the process again.

Because Portuguese treats this as a future or possible condition, not a simple statement of current fact.

Compare:

• Se o molho ficar azedo... = If the sauce turns sour / if the sauce ends up sour
• Se o molho está azedo... = If the sauce is sour...

The second one is much less natural for this kind of conditional idea. After se, Portuguese usually prefers the future subjunctive when talking about something that may happen.

Usually, molho means sauce in cooking contexts.

Examples:

• molho de tomate = tomato sauce
• molho branco = white sauce
• molho pesto = pesto sauce

Depending on context, molho can also refer more broadly to a liquid mixture or dressing, but sauce is the main meaning here.

A more word-for-word breakdown would be:

• Se = if
• o molho = the sauce
• ficar azedo = becomes sour / turns sour
• minha avó = my grandmother
• tira = removes / takes out
• as sementes = the seeds
• do tomate = from the tomato
• e começa de novo = and starts again

So the literal structure is roughly:

If the sauce turns sour, my grandmother removes the tomato seeds and starts again.

That is already quite close to natural English, but it is useful to notice that ficar carries the idea of becoming, not just being.