Dice the carrot and potato into small chunks. Finely dice the onion and mince the garlic.
Heat a large stock pot on a medium heat and add a little oil into the bottom. Once hot, saute the onion until translucent (2-3 minutes) then add the garlic and cook for 1 more minute.
After 1 minute, add in the potatoes and carrots and stir to coat with the onion mixture. Add in the thyme too and cook everything together for 5 minutes until the carrot and potato just begin to soften.
Add the vegetable stock and lentils, cover and simmer for 25-30 minutes, until the vegetables and lentils are completely cooked.
Take off the heat and if desired, use a stick blender to roughly blend the soup. I like to leave some chunks in for texture, but if you prefer completely smooth soup you can blend it more.
Once blended, chop the swiss chard (or whatever kind of dark leafy green you are using) into strips, and stir into the soup. The heat from the soup will wilt the greens so there’s no need to actually cook them.
Soup will keep in an airtight container in the fridge for up to 5 days, or up to 3 months in the freezer.