Let’s think about the Yin and Yang of colors.

Colors like blue and violet have Yin energy, and colors like yellow and red have Yang energy. Blue and violet feel cold, and yellow and red feel warm, don’t they?

When you have a fever, your face is red. When you feel very cold, your face is bluish pale and your lips can be violet.

You can say the same thing about what you eat.

For example, eggplant and strawberries grow above ground so they have more Yin type energy.
The color of eggplant is violet, so the Yin energy of eggplants is very strong. On the contrary, the color of strawberries is red so strawberries have more Yang energy than eggplant.

Potato, sweet potato, taro, etc. grow underground so they have more Yang energy, but they don’t go into the ground. Instead, they expand. It means they have more centrifugal energy, which is Yin energy. When you look at their sprouts, their color is close to violet. Therefore, they are Yang type vegetables, but they have more Yin energy than carrots, burdock, etc which grow into the ground.