Grind those beans
Heat 5 cups (1.25 L) of the reserved water in a large pot over medium-high heat.
PRO TIP: Nonstick pots will make cleanup faster and easier.
While that water warms, grind the beans in the blender with 2 more cups (500 ml) of the reserved soaking water. Puree the mixture until it looks exactly like a milkshake. Pour the blended mixture into the hot pot of water. Rinse out the blender with an additional 1/2 cup (125 ml) of the reserved water, and add it to the pot as well.