Preheat the oven to 350 degrees. Line a baking sheet with foil and spray with nonstick spray.
In a large skillet heat the olive oil on medium heat, once hot, add the onion carrots, mushrooms and garlic. Cook for about 8 minutes, or until the vegetables are soft.
Transfer the cooked vegetables to a food processor along with 1 cup of the lentils, 3/4 cups of the oats, tomato paste, tamari, Worcestershire, thyme, and oregano. Pulse until the mixture is well blended but still a little chunky.
Transfer the processed mix to a large bowl and gently mix in the remaining lentils, oats, and peas. Mix just until combined. Form the mix into a loaf shape onto the prepared baking sheet. Bake for 30 to 45 minutes or until firm. If desired, top with no sugar added ketchup.