Set your Instant Pot to saute mode.
Add the olive oil, along with the onion, bell pepper, carrots, and garlic.
Cook for a few minutes, just until the onion and pepper soften.
Add the ginger, turmeric, curry paste, tomato paste, salt and pepper, and stir everything together well, continuing on saute mode until everything is very fragrant (about 3-4 minutes).
Add the lentils and the vegetable stock, scraping up any caramelized bits on the bottom of the pot.
Hit the cancel button to stop saute mode, and add the lid to the Instant Pot.
Set the valve to the sealing position and set the Instant Pot to cook on High Pressure for 7 minutes.
After the cooking time is finished, release the pressure manually (it's a good idea to do this with a long-handled kitchen tool to avoid burning yourself, and to release the pressure under a hood fan in your kitchen, if you have one).
Remove the lid from the Instant Pot once the pressure is released and pour the coconut milk into the Instant Pot.
Stir well, and turn on sauté mode for just a few minutes (stirring regularly) until the sauce thickens (only do this if the mixture is very liquidy). Add the spinach and stir it in just until it wilts.
Serve over rice with some fresh chopped cilantro and naan bread (optional).