Перед тем как жарить блины, нужно смешать муку и кефир.

Перед тем как is a very common way to say before when it introduces an action.

Literally, the words are something like:

• перед = before
• тем = that / it
• как = how

But as a whole, перед тем как functions as a fixed expression meaning before doing something or before something happens.

In this sentence:

• Перед тем как жарить блины = Before frying pancakes

It introduces a subordinate clause about what happens earlier.

Жарить is an infinitive, meaning to fry.

Russian often uses the infinitive after expressions like перед тем как when the subject is general, implied, or not important. In recipes and instructions, this is especially common.

So:

• Перед тем как жарить блины = Before frying pancakes

Russian does not need to say you here. English also often drops the subject in instructions:

• Before frying the pancakes, mix the flour and kefir.

If you wanted to make the subject explicit, you could say something like:

• Перед тем как вы будете жарить блины... but that is less natural in a recipe-style sentence.

This is a very important Russian aspect point.

• жарить is imperfective
• смешать is perfective

Why?

жарить (imperfective)

Here, frying is treated as a general activity or process:

• before frying pancakes

The sentence is not focusing on the completion of the frying itself. It just refers to that activity as the next stage.

смешать (perfective)

Here, mixing is viewed as one complete action that needs to be done first:

• it is necessary to mix the flour and kefir

The idea is: complete this step, then move on.

So the aspect choice reflects the meaning:

• смешать = complete the mixing
• жарить = the general process/activity of frying

Нужно means something like:

• it is necessary
• one needs to
• you need to

It is an impersonal word, so there is no explicit subject.

In this sentence:

• нужно смешать муку и кефир means
• it is necessary to mix flour and kefir or more naturally in English:
• you need to mix flour and kefir

This kind of impersonal construction is very common in Russian instructions, recipes, and general advice.

Russian often leaves out the subject when it is obvious or not important.

In recipes, manuals, and instructions, Russian commonly uses impersonal constructions like:

• нужно сделать...
• надо добавить...
• следует смешать...

So instead of saying:

• Вы должны смешать муку и кефир Russian often prefers the more neutral:
• Нужно смешать муку и кефир

This makes the sentence sound like a general instruction rather than a direct command.

Because муку is in the accusative case, used here for the direct object of смешать.

The dictionary form is:

• мука = flour

But feminine nouns ending in -а usually change to -у in the accusative singular:

• мука → муку

So:

• смешать муку = to mix flour

This is a regular pattern for many feminine nouns:

• вода → воду
• сметана → сметану

Кефир is also a direct object, so it is in the accusative case too. But for many masculine inanimate nouns, the accusative singular is the same as the nominative singular.

So:

• кефир (nominative)
• кефир (accusative)

That is why it does not visibly change.

Compare:

• Я пью кефир.
• Нужно смешать кефир и муку.

The form stays the same.

For the same general reason: блины is the direct object of жарить, so it is in the accusative case. But for inanimate plural nouns, the accusative usually looks the same as the nominative.

So:

• блины = nominative plural
• блины = accusative plural

That is why the form does not change.

If the noun were animate, the accusative plural would often look different.

Because Перед тем как жарить блины is a subordinate clause, and it comes before the main clause:

• Перед тем как жарить блины, нужно смешать муку и кефир.

Russian separates subordinate clauses from the main clause with a comma.

So the structure is:

• subordinate clause: Перед тем как жарить блины
• main clause: нужно смешать муку и кефир

That is why the comma appears after блины.

Yes. Russian word order is flexible.

For example, you could also say:

• Нужно смешать муку и кефир перед тем, как жарить блины.

This means the same thing.

The difference is mostly about focus and style:

• Перед тем как жарить блины, нужно... emphasizes the time sequence first
• Нужно смешать..., перед тем как... emphasizes the required action first

Both are natural.

Yes, absolutely.

• Нужно смешать муку и кефир
• Надо смешать муку и кефир

Both mean you need to mix the flour and kefir.

A very rough difference:

• нужно can sound a little more neutral or formal
• надо can sound a little more conversational

In everyday speech and recipes, both are common.

Yes, that is also possible:

• Перед жаркой блинов нужно смешать муку и кефир.

This means basically the same thing:

• Before frying pancakes, you need to mix flour and kefir.

But the structure is different:

• Перед тем как жарить блины uses a clause with a verb
• Перед жаркой блинов uses a noun phrase, literally before the frying of pancakes

The version with перед тем как + infinitive often feels more conversational and transparent for learners. The noun version is more compact.