SEAR: Pat the pork cheeks dry with some paper towel, then trim off any loose pieces of fat. Cut the pork cheeks into 2 x 3 inch / 5 x 7.5 cm pieces so that they’re evenly sized. Heat a large skillet over medium heat and add the fat of your choice. Working in batches, sear the pork cheek pieces until they are golden brown on both sides, then transfer them to the insert of the Instant Pot. You can use the “sear” function of the Instant Pot if you would like, but it will take much longer to get all the pieces done, so I prefer to just dirty up a large cast iron skillet.
PRESSURE COOK: Pour the broth over the browned pork cheeks, then add the mushrooms, leek, onion, garlic and sea salt. Check the rubber seal is in place on the lid, that the shield is in place, that the float valve moves freely and that the weight is set to the “sealing” position. Pop the lid on and lock it into the closed position. Use the “Meat and Stews” setting to pressure cook for 45 minutes, until the meat is fork tender.
BLEND: Carefully turn the weight to the “venting” position so that the pressure is quickly released. Remove the pork cheek pieces to a chopping board and use two forks to gently shred them into bite size pieces. Carefully transfer the cooked vegetables and all of the cooking liquid from the Instant Pot to a large blender and add the lemon juice. Make sure that the blender is large enough to handle 5 cups / 1.2 l of hot liquid, making sure to leave part of the lid open to allow steam to escape when blending, covered with a kitchen towel if needed. Blend until you have a smooth, sauce like consistency, then taste and add any extra salt, if needed.
SERVE: Transfer both the shredded meat and the blended liquid to the insert of the Instant Pot and stir through to combine into a silky smooth stew. You can either serve it immediately, or pop the insert back into the Instant Pot and use the “warm” setting to keep it hot until you’re ready to serve.