If making ahead, add extra water when reheating, as the soup will thicken as it cools. This soup is traditionally made with stock from a ham bone but ... to get the classic pea soup flavour.
Break up the ham hock, discarding the skin and bone and pull the meat into pieces. Add the mustard to the soup and season with salt and pepper. Use a stick blender to blend to a rough purée ...
Traditional split pea soup often uses ham for its smoked meat flavor ... Check out Food & Wine's guide to split pea soup for more recipes and ideas on preparing this fail-safe, delicious soup.