Questions & Answers about Я добавляю лук в фарш, чтобы котлеты были вкуснее.
Добавляю is the 1st person singular present tense of the imperfective verb добавлять.
So:
- я добавляю = I add / I am adding
- добавить = to add (the infinitive, perfective)
- я добавлю = I will add (future, perfective)
In this sentence, я добавляю sounds like a habitual or general action: I add onions to the mince...
That fits well if the speaker is describing a cooking method or what they usually do.
It actually is in the accusative case here, but for an inanimate masculine noun like лук, the accusative singular looks the same as the nominative singular.
So:
- nominative: лук
- accusative: лук
This happens because добавлять takes a direct object, and the thing being added is лук.
Compare with a feminine noun, where the change is more visible:
- Я добавляю соль.
- Я добавляю воду.
With лук, you just don’t see the change in form.