Om smeten är för tjock, vispar jag i lite mer mjölk.

Smeten is the definite form of smet, so it means the batter.

In Swedish, nouns usually change form to show definiteness:

• en smet = a batter
• smeten = the batter

Here, the speaker is talking about a specific batter they are already working with, so Swedish uses the definite form.

Here, om means if.

So Om smeten är för tjock means If the batter is too thick.

This is a very common use of om to introduce a condition:

• Om det regnar, stannar vi hemma. = If it rains, we stay home.
• Om du vill, kan jag hjälpa dig. = If you want, I can help.

The comma separates the if-clause from the main clause:

• Om smeten är för tjock, = if the batter is too thick
• vispar jag i lite mer mjölk. = I whisk in a little more milk

In Swedish, a comma is often used after an introductory subordinate clause like this, especially in writing. It helps make the sentence easier to read.

Here, för means too.

So:

• för tjock = too thick
• för varm = too warm
• för dyr = too expensive

This is different from other meanings of för, which can also mean things like for or on behalf of, depending on context. In this sentence, it is the too meaning.

This is because Swedish follows the V2 rule in main clauses: the finite verb must come in the second position.

The first position here is taken by the whole if-clause:

• Om smeten är för tjock = first position

So the finite verb in the main clause comes next:

• vispar = second position
• jag = after the verb

That is why you get:

• Om smeten är för tjock, vispar jag i lite mer mjölk.

If there were no introductory clause, it would be:

• Jag vispar i lite mer mjölk.

Vispa i is a very common combination meaning something like:

• whisk in
• add while whisking
• mix in by whisking

So vispar jag i lite mer mjölk means the speaker adds more milk and incorporates it by whisking.

The i is important here. Without it, vispa just means to whisk in a more general sense. With i, it suggests whisking something into the mixture.

Because vispa i works like a particle verb.

In many Swedish main clauses, the verb and its particle are separated:

• Jag vispar i mjölken.
• Hon häller i sockret.
• Vi blandar i lite salt.

The main verb comes earlier, and the particle often comes later.

So in vispar jag i lite mer mjölk, the i belongs with vispar, even though it is not directly next to it.

Because mjölk is being used as an uncountable substance noun, like milk in English.

You normally do not say:

• en mjölk for a milk when you mean the substance itself

Instead, you say:

• mjölk = milk
• lite mjölk = a little milk
• mer mjölk = more milk
• lite mer mjölk = a little more milk

So this works very much like English.

Lite mer means a little more.

It is made up of:

• lite = a little
• mer = more

Together:

• lite mer mjölk = a little more milk

This is a very common pattern:

• lite mer salt = a little more salt
• lite mer socker = a little more sugar
• lite mer tid = a little more time

Yes. Tjock is the normal word for thick in this context.

For mixtures, sauces, batter, soup, and similar things, Swedish often uses:

• tjock = thick
• tunn = thin

Examples:

• Soppan är för tjock. = The soup is too thick.
• Såsen är lite tunn. = The sauce is a little thin.

So för tjock sounds completely natural here.

Yes, you could. Alltför tjock means something like far too thick or much too thick, so it is stronger than för tjock.

Compare:

• för tjock = too thick
• alltför tjock = far too thick / excessively thick

In everyday language, för tjock is probably the more neutral and common choice in a sentence like this.

Both är and vispar are in the present tense.

• är = is
• vispar = whisk / am whisking

Swedish often uses the present tense for general instructions, habits, or actions in a recipe-like context. English can do something similar:

• If the batter is too thick, I add a little more milk.
• If the batter is too thick, I whisk in a little more milk.

So the present tense here sounds natural and general, like describing what one does in that situation.