In a large pot, on medium heat, add oil, onions, cook until translucent. Add, celery and garlic, cook for 3 minutes.
Then add cubed sweet potatoes, lentils, vegetable broth, diced tomatoes, seasoning, salt and pepper, bring to a boil, then reduce to low heat and simmer for 40 minutes until, sweet potato is soft.
Add chopped kale, cook until wilted, then ready to serve.