Add the oil and onions to a large soup pot and saute on medium high until onions start to become translucent.
Add carrots and potatoes and continue to saute for another 3-5 minutes.
Add vegetable stock and water. Bring to a boil.
Add lentils, barley, apples, frozen vegetables (if using) and all the herbs and seasonings.
Simmer the stew on medium and continue to cook until potatoes and carrots are cooked through and lentils are soft, about 30-40 minutes.
Remove the bay leaves and enjoy!