Heat the onion, carrots and peppers in a pot over medium heat for a few minutes.
Add lentils, broth, turmeric, garlic powder, vinegar, chilli flakes and soy sauce. Stir together and bring to a boil. Once soup has reached a boil, reduce heat to low and simmer, covered for 20 minutes.
Add chopped potatoes and simmer, covered for 15 minutes or until potatoes are tender.
Add kale and simmer for 5 more minutes. Season to taste with salt and pepper