Set the Instant Pot to the Sauté mode for 6 minutes. Once the pot is warm, add the olive oil. Stir in the diced onions and sauté to release the flavors, about 2 minutes, the onions will be slightly transparent.
Add in the carrots and celery, sauté another 2 minutes, the veggies will begin to get soft.
Mix in the minced garlic and stir another 30 seconds to release the flavor of the garlic.
To the Instant Pot, add the vegetable broth and scrape up any brown bits at the bottom of the pot.
Add in the lentils, fire-roasted tomatoes, soy sauce, bay leaf, salt, thyme, oregano, and black pepper. Press cancel on the Instant Pot.
Close the lid and valve. Set the Instant Pot on high pressure for 20 minutes. Allow a natural release, once valve ball drops, open the valve and lid. Remove and discard the bay leaf.
Taste for seasoning, if needed, adjust any seasoning.
This is a very hearty stew and it s wonderful over mashed potatoes or cauliflower. Of course, it can be served on its own too.
Fresh thyme can be sprinkled over the lentils.