Rinse your beans under cold water. Then soak the beans in water for at least 8 hours or overnight. If you are using an instant pot, skip this step.
When the beans are rehydrated and soft, drain them and transfer to a medium-sized pot. If you are using an instant pot, put the beans into your instant pot.
Add 6 cups of water and bring it to a boil. Then reduce the heat and simmer for an hour. For the instant pot, pressure cook at high pressure for 30 minutes + 20 minutes natural release.
After, the beans should be soft enough to squish between your fingers. Use an immersion blender to blend until they are broken up. You can blend more if you prefer a smoother red bean soup.
Transfer the blended mixture back into the pot. Add in the sugar and orange zest. Stir over medium-high heat and dissolve the sugar. For the instant pot, bring the red bean soup to a boil using the "Saute High" function. Let it boil for 15 - 20 minutes until desired thickness. Add in your sugar and orange zest and stir occasionally. For a more soupy consistency, add in more water.
This step is optional if you want tapioca in it. Add in the tapioca pearls and cook until the pearls become translucent, about 20 minutes.
Scoop into serving bowls and let cool for 5 minutes before serving. Enjoy!