Heat the olive oil in a large pot over medium heat. Add the onion and cook until softened, about 5 minutes. Add the garlic, oregano, and thyme and cook for 1 minute more.
Add the lentils, vegetable broth, and bay leaf to the pot. Bring to a boil, then reduce heat and simmer for 30-40 minutes, or until the lentils are tender.
Remove the bay leaf. Stir in the lemon juice and season with salt and pepper to taste.