Learn Hardcore German: Die Köchin mischt alle Zutaten im Mixer und teilt die Suppe in kleine Portionen. - The cook mixes all the ingredients in the blender and divides the soup into small portions.

Here, die Köchin tells you the cook is female.
The article die is the nominative singular article for feminine nouns (die Köchin), and Köchin is the feminine form of Koch.

Why are the verbs mischt and teilt, not mischen and teilen?

German verbs change their endings depending on the subject (who does the action).

The subject is die Köchin = sie (she, singular).
For sie (singular) in the present tense, regular verbs take the ending -t.

mischen (to mix) → sie mischt (she mixes)
teilen (to divide) → sie teilt (she divides)

So:

Die Köchin mischt ...
(Die Köchin) ... teilt ...

Both verbs correctly use the 3rd person singular present tense ending -t.

Why are there two verbs in the middle of the sentence: mischt and teilt? How does the word order work?

The sentence actually contains two main clauses joined by und:

Die Köchin mischt alle Zutaten im Mixer.
(Die Köchin) teilt die Suppe in kleine Portionen.

German main clauses typically have:

subject in first position,
conjugated verb in second position.

So we get:

Clause 1: Die Köchin (1st) – mischt (2nd)
Clause 2: Die Köchin (understood, not repeated) – teilt (2nd)

Because the subject is the same (die Köchin), it is only stated once at the beginning. The und simply joins the two clauses, each with verb in second position:

Die Köchin mischt ... und (sie) teilt ...

Why is there no comma before und in this sentence?

In German, a comma can be used before und when joining two main clauses, but it is often optional if the clauses are short and closely related.

Here you have two main clauses:

Die Köchin mischt alle Zutaten im Mixer
(Die Köchin) teilt die Suppe in kleine Portionen

Both are short and share the same subject, so it is perfectly correct (and common) to write them without a comma:

Die Köchin mischt alle Zutaten im Mixer und teilt die Suppe in kleine Portionen.

You could also write a comma:

Die Köchin mischt alle Zutaten im Mixer, und teilt die Suppe in kleine Portionen.

but many style guides prefer leaving it out in such a simple case.

What cases are used in alle Zutaten, die Suppe, and kleine Portionen?

All of these phrases are in the accusative case, because they are direct objects.

alle Zutaten
- Direct object of mischt (whom/what does she mix?)
- Question: Wen oder was mischt die Köchin? → alle Zutaten
- So Zutaten is accusative plural.
die Suppe
- Direct object of teilt (whom/what does she divide?)
- Question: Wen oder was teilt die Köchin? → die Suppe
- So Suppe is accusative singular feminine (same form as nominative die Suppe).
in kleine Portionen
- This is a prepositional phrase with in
  - Accusative expressing a change of state / result (into what does she divide the soup?).
- Portionen is therefore in the accusative plural: kleine Portionen.

What exactly is im in im Mixer?

im is a contraction of in dem.

in = in
dem = the (dative masculine or neuter)

Mixer is masculine (der Mixer).
When you say there is something in the mixer (location, no movement into it), in takes the dative case:

in dem Mixer → im Mixer

So im Mixer literally means in the mixer (state, inside the mixer).

Why is it im Mixer (dative) but in kleine Portionen (accusative)? Isn’t it the same preposition in?

The preposition in is one of the so‑called two-way prepositions. It can take:

Dative → when talking about a location/state (where something is)
Accusative → when talking about movement/change (where something goes / what it becomes)

In this sentence:

im Mixer (in dem Mixer) – Dative
- Describes where the ingredients are being mixed → a location/state.
- Question: Wo mischt die Köchin die Zutaten? → im Mixer (where?)
in kleine Portionen – Accusative
- Describes what the soup is being turned into → change of state/result.
- Question: Wohinein / Worin teilt sie die Suppe? (into what?) → in kleine Portionen

So same preposition in, but different meaning (state vs change), so different cases (dative vs accusative).

Why is it in kleine Portionen and not in kleinen Portionen?

Because here in expresses a change into something (the result), not a location.

in kleine Portionen = into small portions (result) → Accusative
in kleinen Portionen = in small portions (state, manner) → Dative

Compare:

Sie teilt die Suppe in kleine Portionen.
→ She divides the soup into small portions (she creates those portions).
Die Suppe wird in kleinen Portionen serviert.
→ The soup is served in small portions (it already is in that form; describes the manner/condition).

The sentence you gave clearly describes the result of her action, so Accusative: in kleine Portionen.

How do the adjective endings work in alle Zutaten and kleine Portionen?

Two different patterns:

alle Zutaten
- alle here behaves like a determiner (similar to an article).
- Plural, accusative: alle
  - noun.
- Zutaten is plural; the accusative plural form is the same as nominative plural.
- So: alle Zutaten = all ingredients (direct object).
kleine Portionen
- No article before it (no die, eine, etc.).
- With no article, the adjective must show more of the case and number information.
- Portionen is plural; here it’s accusative plural.
- Adjective ending in accusative plural without article: -e
- So: kleine Portionen (not kleinen here, because that would be dative plural).

Summary:

Plural accusative with a determiner like alle: alle Zutaten
Plural accusative with no article: kleine Portionen

Could you also say mit dem Mixer instead of im Mixer? What’s the difference?

Yes, both are grammatically correct, but they mean slightly different things:

im Mixer (in dem Mixer)
→ Focus on the place where the ingredients are: inside the mixer container.
→ Emphasizes that the mixing happens inside that device.
mit dem Mixer
→ Literally: with the mixer (using the mixer as a tool).
→ Focus on the instrument she uses.

So:

Die Köchin mischt alle Zutaten im Mixer.
= She puts the ingredients in the mixer (e.g. a blender) and mixes them there.
Die Köchin mischt alle Zutaten mit dem Mixer.
= She uses the mixer as a tool to mix them (could be a hand mixer, etc.).

In many contexts both might describe almost the same situation, but im Mixer is more specific about the ingredients being inside the machine.

What tense is this? How would I say “is mixing” and “is dividing” in German?

The sentence is in the present tense (Präsens):

mischt = mixes / is mixing
teilt = divides / is dividing

German usually does not use a separate present progressive form like English “is mixing”. Instead, the simple present Präsens covers both:

Die Köchin mischt alle Zutaten
→ The cook mixes all the ingredients.
→ The cook is mixing all the ingredients.

If you really want to stress that it is happening right now, you can add an adverb:

Die Köchin mischt gerade alle Zutaten.
= The cook is (currently/just now) mixing all the ingredients.

But grammatically it is still just Präsens.

What’s the nuance of teilen in teilt die Suppe in kleine Portionen? Is it like “share” or “divide”?

teilen has several related meanings, but here it means to divide / split into parts.

die Suppe in kleine Portionen teilen
= to divide the soup into small portions.

Other common uses:

den Kuchen teilen
= to divide / cut the cake (into pieces)
etwas mit jemandem teilen
= to share something with someone

In your sentence, there is no necessary idea of sharing with specific people; it simply states that she divides the soup into small, separate portions (maybe so they can be shared later).