aonori wo kakeru.

青のり refers to a kind of green seaweed flake used as a topping. In Japanese food, it is often sprinkled over things like okonomiyaki, takoyaki, or yakisoba.

It is more specific than just のり, which can also refer to the dried seaweed sheets used for sushi.

It is read あおのり.

• 青 = あお
• のり = seaweed

So the full reading is あおのり.

を marks the direct object of the verb.

Here, 青のり is the thing being put on or sprinkled, so it takes を:

• 青のりをかける = to put/sprinkle green seaweed on something

So grammatically, 青のり is the object of かける.

Yes, かける has several meanings, and this is one of the very common things Japanese learners notice.

Depending on context, かける can mean:

• to hang
• to wear something like glasses
• to make a phone call
• to spend time or money
• to pour/sprinkle/apply something onto something

In 青のりをかける, it means to sprinkle or to put on top.

This use is common with toppings and sauces:

• ソースをかける = put sauce on
• 塩をかける = sprinkle salt on
• チーズをかける = put cheese over

So here, context tells you which meaning of かける is intended.

Yes, very likely. Japanese often leaves out information that is clear from context.

A fuller sentence could be something like:

• お好み焼きに青のりをかける。
  = Put green seaweed on the okonomiyaki.

In your sentence, the food receiving the topping is omitted because it is probably already obvious from the situation.

Because Japanese often omits the subject when it is understood from context.

So 青のりをかける。 could mean things like:

• I put green seaweed on it
• You put green seaweed on it
• [We/they] put green seaweed on it
• Put green seaweed on it in an instructional context

Japanese does not need to state the subject as often as English does.

It is in the plain non-past form, often called the dictionary form.

That form can express several ideas depending on context, such as:

• a general action
• a habitual action
• a future action
• an instruction in recipes or manuals

In a recipe or cooking instruction, 青のりをかける。 usually feels like:

• Sprinkle on green seaweed
• Add green seaweed on top

So even though it is not an English-style imperative form, it can function like an instruction.

Both are natural, but they are used in different situations.

• 青のりをかける。 = plain form
• 青のりをかけます。 = polite form

The plain form is very common in:

• recipes
• casual speech
• captions
• step-by-step instructions

The polite form is common in:

• polite conversation
• formal explanations
• speaking to customers or strangers

So in recipe-style language, 青のりをかける。 is completely normal.

With this meaning of かける, the thing being poured or sprinkled usually takes を, and the target can take に.

So the fuller pattern is:

• AをBにかける
  = put/sprinkle A onto B

For example:

• 青のりをたこ焼きにかける。
  = Sprinkle green seaweed on the takoyaki.

In your sentence, only A is shown:

• 青のりをかける。

The target B is omitted.

So 青のりにかける would sound wrong if you mean sprinkle green seaweed. That would make 青のり sound like the target instead of the thing being sprinkled.

Normally, standard Japanese writing does not use spaces like this:

• 青のりをかける。

The spaces in your example are almost certainly there for learners, to make the sentence easier to read and break into parts.

So this is a teaching aid, not normal Japanese punctuation.

Yes. English often just says seaweed, but Japanese has several different words for different kinds.

For example:

• のり = seaweed, often especially the dried sheets
• 青のり = green seaweed flakes used as a topping
• あおさ = another type of green seaweed, similar but not exactly the same

In everyday conversation, learners do not always need to master the botanical difference immediately, but it is useful to know that 青のり is a specific topping word, not just any seaweed.

By itself, yes, especially in a recipe or instruction list.

Japanese recipes often use the plain dictionary form for each step:

• 切る。
• 混ぜる。
• 焼く。
• 青のりをかける。

In that context, it functions like an instruction: sprinkle on green seaweed.

In ordinary conversation, though, the plain dictionary form by itself is not the usual way to give a direct command. A true command would use other forms, but recipes commonly use this neutral instruction style.