Rinse the split peas in water and pick out any pebbles or other debris you see.
Dice the onion, carrot, and celery. Peel the garlic and discard the skin. Chop the garlic.
Set your Instant Pot to the Rice setting on Low Pressure mode.
Melt the butter in the Instant Pot inner pot.
Sauté the diced onions in the butter until softened, about 3 minutes.
Add the diced carrot and celery. Sauté until softened and lightly caramelized, about 5 minutes.
Add the chopped garlic and combine.
Add the split peas, ham hock, broth, bay leaves, salt, and pepper to the sauté mirepoix (vegetables). Add an extra ½ cup of water (I like to use the water to rinse the remaining broth out of the carton.)
Once the broth comes to a boil, turn off the Instant Pot.
Screw the lid in place on the Instant Pot. Turn the steam release handle to Venting.
Set your Instant Pot to the Slow Cook setting and adjust it to the More mode. Set the timer to 5:00 (5 hours).
Leave the soup to cook on the Slow Cook setting. As the soup cooks, the steam release handle might splutter or hiss. This is expected.
If you want to check on your soup, you can open the lid after 2 hours to check the peas are softening and disintegrating.
Once the timer has finished counting down, remove the lid and stir your soup to make sure it's fully cooked. If the peas are still intact and you prefer your split pea soup creamy, set the Slow Cook setting to 1:00 (1 hour) and allow the soup to continue cooking. Repeat until your soup is cooked to your desired consistency.If you like the consistency of your soup, then it's ready to serve.If the soup is too thick, you can add some water to thin it out.
Remove the ham hock before serving. If desired, you can shred the meat and skin on the ham hock and include it in the soup. Or you can discard the ham hock.
Enjoy your split pea soup!
For alternative cooking methods, refer to the advice above about how to cook this recipe on the stovetop.If you insist on cooking the split pea soup in the Instant Pot using the pressure cooking mode for a faster cook time, you can set the Instant Pot to Manual mode. Choose the High Pressure setting and cook the soup on High Pressure for 20 minutes. Remember to set the steam release handle to Sealing.Once the soup has finished cooking, allow the pressure to naturally release for 15 minutes. Then release the remaining pressure by carefully turning the steam release handle to the Venting mode.