Start by boiling lentils and water in a 1:4 ratio in a pot with a spoonful of turmeric and a teaspoon (or more) of salt per every cup.
When the lentils reach a boiling point, turn down the heat to low, and cook the lentils until they soften to your liking, from just-cooked to fall-apart creamy. This can range from 10 to 30 minutes, depending on the variety.
Mix in your other seasonings and add-ons. This can be a combination of fried asafetida and cumin (in the north), curry leaves and coconut (in the south), or even just boatloads of cream (in Punjab). More on all of this soon.