Combine strawberries, sugar, and lemon juice in the Instant Pot. Select SAUTÉ and adjust to NORMAL. Bring mixture to a full boil for about 8 minutes, stirring frequently. Press CANCEL. Secure the lid on the pot. Close the pressure-release valve.
Select MANUAL and cook at high pressure for 8 minutes. When cooking is complete, use a natural release to depressurize. Press CANCEL. Remove the lid. Mash berries with a potato masher. Select SAUTÉ and adjust to NORMAL. Bring mixture to a full boil. Boil for 5 minutes or until mixture reaches gel stage (220°F) stirring frequently. Press CANCEL.
Ladle into half-pint glass jars. Seal jars. Store up to 3 weeks in the refrigerator.