In a large pot over medium heat, add oil and saute onions until translucent. Add ginger, garlic, chili flakes, coriander, cumin, turmeric.
Add potatoes and stir to coat in the spices. Follow with lentils and stir to combine.
Pour in the vegetable stock, cover with the lid and bring to a boil.
Reduce the heat to low and simmer until lentils become tender but the potatoes almost cooked.
Stir in the coconut milk and kale. Add the lime juice. Continue to simmer with closed lid until kale is softened slightly about 3 minutes.
Season with salt if needed and simmer for a few minutes more. Squeeze 1-2 lime wedges into the soup.