1.Heat ghee in a large saucepan over low heat, cook onion, garlic, ginger, chilli, carrot and celery, stirring, until vegetables soften. Add seeds and spices, cook, stirring, until fragrant. Add lentils, tomatoes and stock, simmer, covered, stirring occasionally, for 1 hour or until lentils are tender. Stir in coconut milk, peas and coriander, season to taste.
2.Meanwhile, boil, steam or microwave pumpkin and potato until tender, drain. Mash pumpkin and potato with butter in a medium bowl until mixture is smooth.
3.Preheat oven to 220°C (200°C fan forced). Oil four deep 1¼-cup (310ml) ovenproof dishes.
4.Spoon lentil mixture into dishes, top with mashed pumpkin mixture. Bake, uncovered, 20 minutes or until browned lightly. If you like, sprinkle pies with black sesame seeds.