Cook, stirring continuously, until the vegetables have softened, about 3 minutes.
Add the garlic, salt, Italian seasoning, and pepper, and stir in.
Press CANCEL.
Stir in the broth and lentils.
Add the tomato paste on top but do not stir in.
Close and lock the lid.
Turn the pressure release valve to SEALING.
Press the MANUAL button and adjust the time to 25 minutes on high pressure.
It will take about 10 minutes to come up to pressure before the cooking time begins.
Let the pressure release naturally for 15 minutes.
Turn the pressure release valve to VENTING to release any remaining pressure.
Unlock and remove the lid.
Stir the soup.
Add the fresh spinach leaves, and stir to combine.
Drizzle the soup with a little balsamic vinegar before serving.
Notes
Lentils: You can use green lentils in place of the brown lentils in this recipe.
Veggies: Feel free to add more veggies if you prefer.
Broth: Use vegetable broth to keep the soup vegetarian/vegan.
Balsamic vinegar: The balsamic vinegar adds a bit of sweetness and acidity to the soup (helps to brighten up the soup). If you prefer, you can use another type of vinegar (like red wine).