Heat the olive oil in a medium sauce pan over medium to medium-low heat. Add the onion, celery, carrot, and garlic. Cook, stirring often, until the vegetables start to brown a bit, 8-10 minutes. Add the garam masala and cook for another 3-5 minutes.

Add the lentils and chicken stock, and bring to a boil. Cover, reduce the heat to maintain a simmer, and cook for 10 minutes, stirring occasionally. Add the sweet potato and simmer an additional 10-15 minutes, or until the lentils and sweet potato are tender. ***This is where you may or may not need the water. Add it in if the stew looks too thick; if there isn't enough liquid the lentils won't cook properly***

Stir in the baby kale, remove the pot from the heat, and allow the kale to wilt for about 10 minutes. (If you are using mature kale, simmer for 5-7 minutes.) Season with salt and pepper.