Heat the oil in a large pot over medium heat. Add the onion and cook until softened, about 5 minutes.
Add the garlic and cook for 1 minute more.
Add the frozen mixed vegetables, diced tomatoes, lentils, vegetable broth, thyme, and smoked paprika. Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until the lentils are tender.