Если тесто получилось слишком густым, добавь ещё кефира или воды.

Получилось comes from получиться, which often means to turn out, to come out, or to end up in a certain way.

So:

• тесто было слишком густым = the dough/batter was too thick
• тесто получилось слишком густым = the dough/batter turned out too thick

In cooking, получиться is very common because it focuses on the result after mixing, baking, etc.

Because it agrees with тесто, which is a neuter singular noun.

In the past tense, Russian verbs agree with gender and number:

• masculine: получился
• feminine: получилась
• neuter: получилось
• plural: получились

Since тесто is neuter, you get тесто получилось.

After verbs like получиться, стать, оказаться, Russian often uses the instrumental for the adjective that describes the result.

So:

• тесто получилось густым = the dough turned out thick

This is a very common pattern:

• стать лучше
• оказаться полезным
• получиться вкусным

Using густое here would sound wrong in standard Russian for this structure.

The full verb is получиться. The -ся / -сь is part of the verb itself.

In this sentence, you do not need to interpret it literally as a reflexive it got itself. It is simply the normal dictionary form of the verb meaning to turn out / to come out.

So learners should usually treat получиться as its own verb with its own meaning.

Добавь is the singular informal imperative of добавить: add.

It is used when speaking to:

• one person
• informally
• in recipe-style instructions

Compare:

• добавь = add (to one person, informal)
• добавьте = add (to several people, or to one person formally)

Recipes often use this kind of imperative.

This is a question of aspect.

• добавить → perfective
• добавлять → imperfective

Добавь is perfective, so it presents the action as one complete step: add some more liquid.

That fits recipe instructions very well: first check the consistency, then add more kefir or water.

Добавляй would sound more like:

• keep adding
• add gradually / as an ongoing process
• a repeated or process-focused action

So добавь is the natural choice here.

Because after ещё with mass nouns, Russian very often uses the genitive to mean some more of something.

So:

• ещё кефира = some more kefir
• ещё воды = some more water

This is sometimes called the partitive/quantity genitive.

Compare:

• добавь воду = add water
• добавь ещё воды = add some more water

The genitive here emphasizes an indefinite amount, not a specific whole item.

Russian often leaves out subject pronouns when the verb form already makes the meaning clear.

In добавь, the verb itself already tells you this is a command to you (singular informal), so ты is unnecessary.

Including ты would usually add emphasis, and in a recipe or instruction it would normally be omitted.

Yes, получится is also possible, but the nuance is a little different.

• Если тесто получилось слишком густым... = if the dough has turned out too thick / if it turned out too thick
  This sounds like you have already mixed it and are now judging the result.

• Если тесто получится слишком густым... = if the dough turns out too thick
  This sounds more like a general instruction about a possible future outcome.

Both are possible in cooking context. The past tense version feels very natural when reacting to the result that is already in front of you.

Because Если тесто получилось слишком густым is a subordinate clause introduced by если.

In Russian, clauses introduced by если are normally separated from the main clause by a comma:

• Если тесто получилось слишком густым, добавь ещё кефира или воды.
• Добавь ещё кефира или воды, если тесто получилось слишком густым.

So the comma is required here.