After cooking remove the pot and set it aside for half an hour or so the oil will come on top it is true for for any salan , while it is cooking the oil keeps blended with all other ingredients , once you give time for oil to settle on top of your salan, it will.
Try it I guarantee it will work.
P.S: And if you want to warm up any salan make sure either you give time to oil to settle on top or take out that oil and warm up your salan and add the oil afterward.