In Indian cooking, what does it mean when a recipe says "until the oil begins to leave the side of the pan"? In many Indian recipes I see the phrase "cook until the oil leaves the side of the pan". For example, this recipe says:


  Add tomato puree and cook until oil leaves the side.


Similarly, this one says: 


  [C]ook the gravy until the oil leaves the sides of the pan.


Is this the same as "cook until the oil separates" as described in this other question? Or is it something different? Since the other question talks about the oil leaving the curry/gravy rather than the "sides of the pan", they seem to be different phenomena. Thanks for your help!
Since I'm not an expert in Indian cuisine, I can't say this for certain, but I agree with the comments so far that this seems basically equivalent to the separation of the oil from the curry.

To my mind, the wording makes perfect sense, because in some cases with a lot of oil/butter, you can get separation happening early on the pan's edges.  Oil tends to float on top, and usually the center of a pan is heated more strongly over a burner.  Thus, you tend to get boiling/bubbling in the center, which tends to push any floating oil toward the edges.

But these recipes are not looking for that small amount of oil along the edge (which, depending on stirring and the thickness of the curry, can stay there through much of the cooking process).  They are specifically waiting for the time when separation increases and fat appears floating on the surface even away from the edges of the pan.