Eu gosto de sopa de abóbora ao jantar.

Yes, you often can leave out eu in Portuguese, because the verb form gosto already shows that the subject is I.

So both of these are natural:

• Eu gosto de sopa de abóbora ao jantar.
• Gosto de sopa de abóbora ao jantar.

Including eu can add emphasis, contrast, or clarity. For example, you might say Eu gosto, mas ele não — I like it, but he doesn’t.

Because the verb gostar normally takes the preposition de.

So in Portuguese, you like of something, structurally speaking:

• gosto de sopa
• gostas de café
• gostamos de música

This is a very common pattern and needs to be memorised as part of the verb:

• gostar de + noun / infinitive / pronoun

Examples:

• Gosto de chocolate.
• Gostas de ler?
• Ela gosta de ti.

They do two different jobs.

• The first de belongs to the verb gostar de:
  gosto de sopa = I like soup
• The second de links sopa and abóbora:
  sopa de abóbora = pumpkin soup

So the structure is:

• gosto de
  • sopa de abóbora

This kind of repetition is completely normal in Portuguese.

Portuguese usually expresses this idea with de:

• sopa de abóbora = pumpkin soup
• sumo de laranja = orange juice
• bolo de chocolate = chocolate cake

English often puts one noun directly before another, but Portuguese usually uses de to connect them.

Ao jantar means at dinner, for dinner, or at dinnertime, depending on context.

In this sentence, it means that dinner is the meal at which the speaker likes to eat pumpkin soup.

The phrase is made of:

• a + o = ao
• jantar = dinner / the evening meal

So:

• ao jantar = at dinner / for dinner

In European Portuguese, this is a very natural way to talk about meals.

Because the usual expression for meals here is ao + meal noun in many contexts:

• ao pequeno-almoço
• ao almoço
• ao jantar

This often means for / at that meal.

No jantar is possible in some contexts, but it more often refers to at the dinner event or during the dinner, especially a specific dinner. For a general habit like this sentence, ao jantar is the more natural choice.

Here, jantar is a noun, meaning dinner.

But jantar can also be a verb, meaning to have dinner / to dine.

Compare:

• Ao jantar, gosto de sopa.
  Here jantar is a noun.
• Vou jantar agora.
  Here jantar is a verb.

So the same word can have both functions, and the structure around it tells you which one it is.

After gostar de, Portuguese often uses a noun without an article when speaking generally.

So:

• Gosto de sopa de abóbora. = I like pumpkin soup / I like eating pumpkin soup

If you say gosto da sopa de abóbora, that usually sounds more specific, as if you mean:

• I like the pumpkin soup
• perhaps a particular one already mentioned

So:

• de sopa de abóbora = pumpkin soup in general
• da sopa de abóbora = a specific pumpkin soup

Because de has several uses, and here context makes it clear.

In food expressions, noun + de + ingredient is extremely common:

• sopa de abóbora
• gelado de morango
• tarte de maçã

So sopa de abóbora is naturally understood as pumpkin soup, not the soup belonging to the pumpkin.

In European Portuguese, gosto is approximately pronounced like GOSH-too, but with Portuguese sounds, not English ones.

A rough guide:

• gos- sounds close to gosh
• -to is a reduced final syllable, not a strong English toe

The o sounds in European Portuguese are often more reduced than English speakers expect.

A rough European Portuguese pronunciation is something like uh-BO-bu-ruh, but the unstressed vowels are reduced.

Important points:

• the stress is on bó
• the first and last vowels are weaker than in English
• European Portuguese often reduces unstressed vowels quite strongly

So don’t pronounce every vowel fully like in English.

Yes, it fits European Portuguese very naturally, especially because of ao jantar.

A Brazilian Portuguese speaker would understand it perfectly, but in Brazil people might more often say things in slightly different ways depending on region and style.

For Portugal, this sentence sounds normal and idiomatic.

Yes, absolutely.

• Eu gosto de sopa de abóbora ao jantar.
• Eu gosto de comer sopa de abóbora ao jantar.

The version without comer is shorter and very natural. Portuguese often leaves out to eat when the meaning is obvious from the food noun.

Adding comer makes it more explicit:

• I like to eat pumpkin soup for dinner

Without comer, it still clearly means that.

The structure is:

• Eu = subject
• gosto de = verb + required preposition
• sopa de abóbora = object/complement
• ao jantar = time/meal expression

So:

• Eu
• gosto de
• sopa de abóbora
• ao jantar

This is a very useful pattern to learn:

• (Eu) gosto de + food/drink + ao almoço / ao jantar / ao pequeno-almoço

Examples:

• Gosto de peixe ao jantar.
• Gosto de café ao pequeno-almoço.