Meine Mutter kocht Spinat mit Erbsen, während ich die Avocado schneide.

Because Mutter is a feminine noun in German: die Mutter.

The possessive word mein changes its ending to match the noun’s gender, case, and number. Here, Mutter is:

• feminine
• singular
• nominative (the subject of the sentence)

So mein becomes meine:

• mein Vater
• meine Mutter

That is why the sentence says Meine Mutter kocht ...

Because meine already works like a determiner, similar to my in English.

In German, you normally do not say both a possessive and an article together in this kind of phrase. So:

• meine Mutter = my mother
• not die meine Mutter

The possessive word takes the place of the article.

Because the subject is meine Mutter, which is third person singular: she.

The verb kochen means to cook. In the present tense:

• ich koche
• du kochst
• er/sie/es kocht
• wir kochen
• ihr kocht
• sie/Sie kochen

So with meine Mutter, you need kocht.

Here, Spinat is being used as a food item in a general sense, like an uncountable noun or mass noun.

German often omits the article with food when speaking generally:

• Ich esse Brot.
• Sie trinkt Kaffee.
• Wir kochen Spinat.

If you wanted to refer to a specific spinach, you could use an article:

• Meine Mutter kocht den Spinat.
  = She is cooking the spinach / that specific spinach.

So Spinat without an article is completely natural here.

The preposition mit always takes the dative case.

So after mit, the noun phrase must be in dative:

• mit der Suppe
• mit dem Kind
• mit den Erbsen

In this sentence, there is no article, so you just see Erbsen by itself. Since Erbsen is already plural and ends in -n, its dative plural form looks the same.

So:

• mit Erbsen = with peas

Because während ich die Avocado schneide is a subordinate clause.

In German, subordinate clauses are usually separated from the main clause by a comma. The structure is:

• Main clause, subordinate clause
• or Subordinate clause, main clause

So here:

• Meine Mutter kocht Spinat mit Erbsen, während ich die Avocado schneide.

The comma is required.

Because während introduces a subordinate clause, and in German subordinate clauses, the conjugated verb usually goes to the end.

Compare:

• Main clause: Ich schneide die Avocado.
• Subordinate clause: während ich die Avocado schneide

This is one of the most important word-order rules in German.

So:

• Meine Mutter kocht ... = normal main clause word order
• während ich die Avocado schneide = subordinate clause, so the verb goes to the end

Because Avocado is a feminine noun in German:

• die Avocado

Here it is the direct object of schneide, so it is in the accusative case. For feminine nouns, the article stays die in both nominative and accusative:

• Nominative: die Avocado ist reif
• Accusative: ich schneide die Avocado

So the form does not change here.

In a normal independent sentence, you would say:

• Ich schneide die Avocado.

But after während, you are in a subordinate clause, and German pushes the conjugated verb to the end:

• während ich die Avocado schneide

So the word order changes because of the conjunction, not because the meaning changes.

Here, während means while or during the time that.

It shows that the two actions happen at the same time:

• Meine Mutter kocht ...
• ich schneide ...

So the sentence describes simultaneous actions.

Yes. German allows that very naturally:

• Während ich die Avocado schneide, kocht meine Mutter Spinat mit Erbsen.

That means the same thing.

Just remember: when a subordinate clause comes first, the main clause still follows the normal verb-second rule, so you get:

• ..., kocht meine Mutter ...
• not ..., meine Mutter kocht ...

Not exactly.

• während = while, emphasizing that two things happen at the same time
• wenn = when/whenever/if, often for repeated events or conditions
• als = when, usually for a single event in the past

Examples:

• Während ich koche, hört er Musik.
  = The two actions happen simultaneously.
• Wenn ich koche, höre ich Musik.
  = Whenever I cook, I listen to music.
• Als ich gestern kochte, hörte ich Musik.
  = When I cooked yesterday...

So während is the best choice here because the sentence focuses on two ongoing actions happening at the same time.

Yes. In this sentence, Spinat mit Erbsen naturally sounds like spinach with peas as part of what the mother is cooking.

So the structure is:

• kocht = verb
• Spinat = what is being cooked
• mit Erbsen = an added description, meaning with peas

It sounds like one combined food idea rather than two completely separate actions.

Yes. Both verbs are in the present tense:

• kocht
• schneide

In German, the present tense is often used both for:

• general present
• actions happening right now

So this sentence can very naturally mean that the mother is cooking and the speaker is cutting the avocado at this moment.