The result of THOUSANDS of years of recipe experimentation. When the Char Siu recipe says to use WHITE pepper, then do NOT use black pepper. I learned this lesson on my first batch when I used regular chicken bouillon instead of POWDERED chicken bouillon. It makes a YUUUUUGE difference.
Love to use chicken powder! And my husband only uses white pepper at home. Y’all should try it; it’s an entirely different taste than black pepper, but you still get some heat -— actually, a little more heat, but without the bite of black pepper.