Preheat conventional oven to 200 degrees C/ 392 F and line a baking tray with greaseproof paper. Cut sweet potato into fries of preferred thickness, distribute evenly on the baking tray and sprinkle with 1/2 tsp paprika, and salt and pepper to taste. Bake for 25-30 minutes, until crispy on the outside and soft on the inside.
Meanwhile, heat some oil or cooking spray in a non-stick saucepan. Add the red onion, bell pepper and garlic, stirring for 2-3 minutes on a medium heat.
Add the lentils, canned tomatoes, coconut milk, garam masala, cumin, the rest of the paprika and tomato paste. Bring to a boil and lower the heat.
Simmer for 10-15 minutes, stirring occasionally, until the consistency thickens. Add more canned tomatoes or coconut milk if necessary.
Take off the heat and stir in the kale. Serve immediately with the sweet potato fries and soy yoghurt.