Gather the legumes in a bowl and soak them overnight. Alternatively, you can measure out 16 oz of mixed canned legumes for this recipe, rinse them well, and set aside.
Select the “sauté” mode on your Instant Pot. Add olive oil, heat it for 1 minute, then sauté the ham in there for 1 minute.
Add garlic, onion, carrot, and celery. Cook for 3 minutes.
Add the drained (or rinsed, if you’re using canned) lentils, beans, corn, bay leaf, and butter, and stir around a couple of times.
Add chicken broth, close the lid, and switch the steam handle to “sealed” position. Select “meat stew” mode and adjust the timer to cook for 25 minutes.
Place a kitchen towel or a piece of cloth over the valve (so the steam doesn’t get everywhere), and turn the steam handle to “venting” position. Stir in salt and pepper.
Ladle the soup into serving bowls and sprinkle with a generous amount of coriander.