Heat the vegetable oil in a heavy-based saucepan, add the onion and cook over a high heat, stirring, for 1 minute, then stir in the curry paste and lentils.
Pour in the coconut milk, then fill the can with water and add to the pan along with the vegan vegetable stock. Simmer briskly, uncovered, for 8–9 minutes until the lentils are tender and the mixture is thick and pulpy. Season with pepper and sprinkle over the chopped coriander.
Meanwhile, lightly toast the naans under a preheated hot grill until warm and golden.
Cut the toasted naan into fingers and serve alongside the dahl for dipping.