Set the Instant Pot to sauté after adding the onion, carrots, and celery.
For three minutes, sauté while stirring constantly to prevent scorching.
For 30 more seconds, add the cumin, smoked paprika, and garlic.
Add the vegetable broth, diced tomatoes, and red lentils.
Stop using the sauté feature. then 12 minutes of manual pressure cooking. The Instant Pot will reach pressure in about 10 minutes, at which point the timer will start to count down.
Quick-release the pressure by turning the venting knob to "vent" once the Instant Pot has finished cooking. This will let the steam out. Remove the lid after the steam has evaporated.
Add the lemon juice after allowing it to slightly cool.