Measure the lentils into a strainer and rinse under cool water. Drain. Add to a medium saucepan with vegetable broth. Bring to a rapid simmer over medium high heat, then reduce to a low simmer. Allow to simmer for 20-30 minutes. Drain off any excess liquid and set aside.
Preheat oven to 425 degrees Fahrenheit. Line a large baking sheet with parchment paper and coat with non stick spray.
Meanwhile, heat the olive oil in a medium skillet over medium-low heat. Once hot, add the onion and cook until the onion is translucent and lightly browned, 6 to 8 minutes. Stir in the carrots and cook for another 2 minutes, then stir in the garlic and cook until fragrant.
Place the oats and parsley in a food processor and pulse. Add the lentils, onion mixtures, tomato paste, oregano, salt and pepper. Combine the mixture in the food processor. Add the egg and pulse. Set aside and let rest for 10 minutes.
Roll the lentil mixture into 1 1/2 inch balls. Arrange them in a single layer on the baking sheet. Cook for 10 minutes, rotate and cook for another 10 minutes. Meatballs should be browned or lightly crisp.