Hier, nous avons oublié le tamis, et la pâte avait moins bon goût.

Both are possible.

• Hier, nous avons oublié le tamis... puts hier at the front for emphasis or to set the time right away.
• Nous avons oublié le tamis hier... is also grammatical and means the same thing.

The comma after Hier is common when a time expression is moved to the beginning of the sentence.

Avons oublié is the passé composé, a very common French past tense.

It is formed with:

• avoir in the present: nous avons
• the past participle: oublié

So:

• nous avons oublié = we forgot

French uses the passé composé for a completed action in the past. Forgetting the sieve is a single finished event, so this tense fits well.

This is a very common French past-tense contrast.

• nous avons oublié = a completed event
• la pâte avait moins bon goût = a state or ongoing situation in the past

Here, avait is the imparfait of avoir. The imparfait is often used for:

• background description
• states
• habits
• ongoing situations in the past

So the sentence contrasts:

• the action: we forgot the sieve
• the resulting situation/description: the dough tasted less good

You could say a eu in some contexts, but avait sounds more natural here because it describes how the dough was.

Because oublié is used with avoir.

In French, past participles usually do not agree with the subject when the auxiliary is avoir, unless a direct object comes before the verb.

Here:

• nous avons oublié
• the direct object le tamis comes after the verb

So oublié stays unchanged.

French usually uses an article where English sometimes does too, and sometimes does not.

Here, le tamis means:

• the sieve
• the sifter

The article le is used because the sentence refers to a specific item: the sieve that was needed or expected in that situation.

French generally does not drop articles as often as English does.

Un tamis is a sieve, strainer, or sometimes sifter, depending on context.

In a baking context, it is often the tool used to sift flour or other dry ingredients.

So oublier le tamis means forgetting that kitchen tool.

Pâte is a feminine noun, so it takes la in the singular:

• la pâte = the dough / batter / paste

The exact English translation depends on context:

• in baking, often dough or batter
• in other contexts, it can mean paste

Here, because of tamis, a baking context is likely.

Literally, it is something like:

• had less good taste

But natural English would usually be:

• tasted less good
• didn’t taste as good
• had a less good flavor

This is a very French way of expressing comparison with bon:

• bon goût = good taste
• moins bon goût = less good taste

In English, we would normally rephrase it more naturally.

Because avoir bon goût, avoir mauvais goût, and similar expressions often work as fixed idiomatic patterns in French.

So French can say:

• ça a bon goût
• ça a mauvais goût
• ça a moins bon goût

without using un.

This may feel unusual to an English speaker, because English would often prefer:

• it has a good taste
• or more naturally, it tastes good

In French, avoir goût in this kind of expression does not always need an article.

It is understandable, but it is less natural here.

The more idiomatic phrasing is:

• la pâte avait moins bon goût

French often prefers moins bon directly with goût in this expression.

A phrase with un goût... is possible in other structures, especially when the taste is described more specifically, for example:

• la pâte avait un goût étrange
• la pâte avait un goût plus prononcé

But in your sentence, avait moins bon goût is the more natural choice.

Because moins bon means less good, while pire means worse.

They are related, but not identical.

• moins bon = not as good
• pire = worse

French often uses moins bon in taste comparisons, especially in everyday speech.

So:

• la pâte avait moins bon goût = the dough didn’t taste as good / had a less good taste
• la pâte avait un pire goût would sound unnatural here

If you wanted worse, French would more naturally say something like:

• la pâte avait un goût pire in some contexts, though even that is less common
• more naturally, French would often rephrase the whole sentence

The circumflex in goût is part of the standard spelling of the word.

Historically, many French circumflexes reflect an older s that disappeared over time. This is why goût is related to English gust and taste through older forms.

You do not need to overthink it for grammar purposes: just learn the spelling as part of the word.

The same is true for pâte.

Roughly:

• pâte sounds like paht
• goût sounds like goo

A few notes:

• the â in pâte is a broad a sound
• the ou in goût sounds like oo in food
• the final t in goût is normally silent

So the phrase la pâte avait moins bon goût is roughly:

• la paht ah-veh mwan bohn goo

That is only an approximation, but it may help at first.

Yes. In everyday spoken French, on is very often used instead of nous.

So a more conversational version would be:

• Hier, on a oublié le tamis, et la pâte avait moins bon goût.

This still means Yesterday, we forgot the sieve, and the dough didn’t taste as good.

The version with nous is completely correct, but it sounds a bit more formal or careful than everyday speech.