Add the vegetable stock, lentils, corn, cumin, curry powder, cayenne, salt, and pepper; mix until combined. Bring to a simmer. Reduce heat to low, cover and cook for 15 minutes, stirring occasionally, until the lentils are completely tender.
Using an immersion blender or traditional blender working in batches, puree the soup until it reaches your desired consistency. Return pureed soup to the pot, and stir in the lemon zest and juice until combined.