Place rinsed lentils and dal, ginger, bay leaves and cinnamon in a large pan with 6 cups of cold water. Bring to the boil, reduce the heat to medium and simmer, stirring to prevent sticking for 15 to 20 minutes
Drain lentils into a large colander, remove bay and cinnamon, and rinse well. Return to large pan.
Heat the butter in a medium frypan over medium high heat. Add the onion and cook for 3 minutes. Stir in the garlic, turmeric, cumin, garam masala, and chilli flakes and cook for a further minute until fragrant. Add the lemon juice and season to taste with salt.
Add onion mixture to the lentils and stir through well. Add tomatoes and cocont milk, combine.
Simmer mixture for around another 30 minutes, stirring often, until lentils are cooked and mixture has thickened to your liking.
Serve sprinkled with coriander.
Great with naan bread and pappadums.