In Toronto Canada, I've bought different BIG, raw scallop species like at Whole Foods Market. They are big like HK restaurants'. After I add oil to pan on cook top and stir fry them, they shrink. Why? See photos –
Now see HK restaurants' wok fried scallops Jade Scallops – 西蘭花炒帶子 in Chinese. Top to bottom – House of Canton in Kowloon Tong (first photo beneath),Ming Kee Restaurant in Wan Chai, 金龍冰室 in Tai Po 大埔, Joy Point Dim Sum in Tsim Sha Tsui.
Best Answer
Regarding the scallops shrinking, it could simply be the difference in dry vs. wet scallops. Most grocery stores sell wet scallops. At times, dry scallops can be quite hard to find at retail. Wet scallops naturally shrink because of the loss of so much moisture when cooking.
Also, the higher the heat and longer the cook time, the more the moisture is lost.