Set the Instant Pot to sauté. It should read “30”.

Add butter and onion. Saute for 10 minutes, stirring frequently.

Add celery stalks, fennel, and garlic. Saute 6 more minutes.

Push vegetables to the sides of the pot so there’s a “hole” in the middle, exposing the metal bottom of the pan. Add the mustard seeds to the middle of the pan and stir, toasting the seeds for 2 minutes.

Add the allspice to the center with the mustard seeds and toast for 2 more minutes.

Turn off the sauté feature.

Add 2 cups water to the pot and stir.

Remove 1 cup of the broth and process in a blender till smooth. Return the processed stock to the pot. Stir.

Add the corned beef, bay leaf, tomato paste, cabbage, turnips, salt, and pepper. Fill the instant pot up with water till it nears the Max Fill line. Do NOT fill it higher than this line.

Place the lid on the Instant Pot, turn the vent to “sealing”, and set the Instant Pot to cook for 30 minutes on high pressure.

While the cabbage soup cooks, dice the parsley and fennel fronds, being careful not to use any of the harder stems of the fennel.

When the soup is done cooking, allow the Instant Pot to sit and slow release pressure for 15 minutes. After 15 minutes, you may set the vent to “venting” to release the remainder of the pressure.

When the pressure cooker is done venting, open the pot. Add the parsley, fennel fronds, and lemon juice, and stir. Serve and enjoy!