Add the rapeseed oil, onion, garlic, stock cubes and leek to the bottom of the Instant Pot pan, along with 1 cup of water. Set the machine to saute, and stir until the strong flavours are well combined. This took a few minutes for me.
Add the remaining ingredients, along with salt and pepper to your taste. IMPORTANT: Ensure you don't go over your pressure cooker maximum levels for high liquid content.
Stir the mixture and select the soup setting, which runs for 30 minutes.
Allow the pressure to release naturally.
Using an immersion blender, whizz away until you get the texture you are looking for.
Serve, or use the keep warm setting if you need to wait for a while.