The lentils go in first since they take the longest to cook. Only add salt when the lentils are cooked since salt will keep the lentils from cooking through when added together. When cooked, they will disintegrate into the sauce and thicken the stew.
Add some cooked diced chicken for a non-vegetarian version.
Add some green peas to the sauce.
Frying off the curry paste and spices will release their flavour but do not burn them. The spices and seasoning is to taste.
Add some hot water if the sauce seems to dry. Bind the sauce if need be with corn flour mixed with some cold water.
Ideally, use the pataks cumin coriander mild curry paste for this recipe.
Sambar is reflective of a broad and ancient tradition of lentil-based vegetable stews in southern India.