butabara ni hi wo toosu.

豚バラ means pork belly.

More literally:

• 豚 = pig / pork
• バラ = belly / side meat

In cooking, 豚バラ often refers to pork belly slices, and in recipes it can be short for 豚バラ肉. Japanese recipes often shorten ingredient names when the meaning is clear.

It is read ぶたバラ.

• 豚 = ぶた
• バラ is written in katakana because this meat cut is commonly written that way in recipes and supermarkets.

So the full sentence is read:

ぶたバラ に ひ を とおす。

火を通す is a very common cooking expression meaning:

• to cook through
• to heat thoroughly
• to make sure it is no longer raw

Literally, it is something like to pass heat/fire through, but in natural English that becomes cook through.

So 豚バラに火を通す means cook the pork belly until the heat goes through it, meaning it is properly cooked.

In 豚バラに火を通す, the に marks the thing that the heat is being applied to.

You can think of it like:

• 豚バラに = into/through the pork belly
• 火を通す = pass heat through

So the structure is not exactly cook pork belly as a direct object. It is more like apply heat to the pork belly until it goes through.

This is why に is natural in this set phrase.

Good question. In this expression, 火を通す acts like a set phrase.

Here:

• 火 is the thing being passed through
• so it takes を
• 豚バラ is the target that receives that heat, so it takes に

So grammatically, the sentence is built like this:

• 豚バラに = to the pork belly
• 火を通す = pass heat through

Even though in English pork belly feels like the main object, Japanese organizes this expression differently.

The basic meaning of 通す is to let something pass through.

Examples in other contexts:

• 風を通す = let air through
• 光を通す = let light through

So in cooking:

• 火を通す = let heat pass through the food

That gives the idea of cooking something all the way through, not leaving the inside raw.

Yes, it is complete enough in a recipe context.

Japanese recipes often use short, plain-form instructions like:

• 切る = cut
• 混ぜる = mix
• 焼く = grill/fry
• 火を通す = cook through

So 豚バラに火を通す。 is a recipe-style instruction. In more explicit English, it would be something like:

• Cook the pork belly through.
• Cook the pork belly until it is no longer raw.

The subject is omitted, as it often is in Japanese.

Because 通す is the transitive form, meaning to pass something through.

• 通る = to pass through, to go through
• 通す = to pass something through

In 火を通す, the speaker is actively causing the heat to go through the meat, so 通す is used.

If you used 通る, the meaning and structure would be different.

Yes, but the meaning changes.

• 焼く = grill, fry, roast
• 炒める = stir-fry
• 火を通す = cook through

So:

• 豚バラを焼く focuses on the cooking method
• 豚バラを炒める focuses on stir-frying
• 豚バラに火を通す focuses on the result: the meat is no longer raw

A recipe may use 火を通す when the exact method matters less than making sure the ingredient is properly cooked.

Recipes in Japanese usually use short, plain dictionary-form verbs because they are concise and neutral.

So recipe steps often look like:

• 玉ねぎを切る。
• 肉を炒める。
• 水を加える。

This does not sound rude in a recipe. It is just a standard instructional style.

If you said 豚バラに火を通してください, that would sound more like directly telling someone Please cook the pork belly through.

No. Normally Japanese is written without those spaces:

豚バラに火を通す。

Spaces are often added in teaching materials to make the parts of the sentence easier to see:

• 豚バラ
• に
• 火
• を
• 通す

So the spaced version is for learning, not normal everyday writing.