Dissolving cocoa in liquid It seems like cocoa powder is very tricky to dissolve in liquid without using a slurry. So how do store-bought cocoa mixes dissolve so easily?
Commercial cocoa is frequently "dutched" or treated with alkalai, which increases the dispersibility of the powder. 

"The process darkens the cocoa ingredients, changes the taste by reducing bitterness, and increases the dispersability of cocoa powder for various applications such as beverages".

Source (paywall, sorry): https://www.ncbi.nlm.nih.gov/pubmed/18710243