There are lots of studies about onion benefits and it's been proved that it helps us maintain good health.
Onion is beneficial for symptoms related to Qi stagnation and blood stagnation as it promotes Qi flow. Also, eating onion with Qi-replenishing food works better for Qi deficiency symptoms. 

Here are what onion do to your body in Yakuzen theory.

Nature – Warm（温）
Channels – Spleen (脾), Stomach (胃), Lung (肺), Heart (心)
Flavor – Pungent (辛), Sweet (甘)

How does onion help you?

1. Improve spleen functions and promote Qi flow
2. Regulate stomach functions and improve digestion
3. Induce sweating and promote yang energy flow
4. Detox
5. Lower blood pressure

Good for the following symptoms

1. Poor appetite
2. Bloating stomach
3. Indigestion
4. Diarrhea
5. Burping
6. Nausea
7. Heavy stomach
8. Sensitivity to cold

Japanese home dishes with onion

1. Tamanegi no Okaka Ae (Onion salad with bonito flake)
   Benefits - Nourish Qi and blood / Improve Qi and blood flow / Help kidney functions and increase kidney essence (jing).

Main ingredients
Onion, bonito flakes, vinegar, sugar, soy sauce, lemon juice

For more details, send me a message.

Cautions

It's very important to know about your body conditions before choosing foods.
Do not eat too much of particular foods at once.
Do not eat the foods you are allergic to.
There are foods to avoid if you are pregnant / have a disease. Ask your doctor before you start Yakuzen.