Heat the oil and butter in a medium non stick pan and add the cumin seeds and curry leaves. Allow to cook for 1 minute.
Add the garlic and saute for about a minute over a medium, low heat.
Now turn the heat up slightly so it is medium high, stir in the chopped onion and cook till light brown. This takes about 7 - 8 minutes.
Mix in the dill leaves, salt, turmeric and chilli till combined.
Add the uncooked daal to the mixture and turn the heat right down.
Pour in the water and cover the pan with a tight fitting lid. Cook for 25 minutes, checking at the 20 minute mark to make sure it isn't sticking. If it is catching, add 1/2 cup water.
The daal should still be firm to the touch.
Serve with a squeeze of lemon.