One of the most important rules in dumpling making is ensuring your filling is completely cooled before assembling. Hot filling causes several problems: it softens the dough, making it sticky and nearly impossible to handle or seal properly. Warm filling also generates moisture that weakens the dough from the inside, leading to tearing during folding or bursting during cooking. Professional dumpling makers spread their cooked filling onto a cold tray to accelerate cooling. If pressed for time at home, spread the filling thinly on a plate and place it in the freezer for a few minutes. Patience at this stage prevents the heartbreak of burst dumplings later on.