I wanted them to get really well browned, so I let them do their thing over medium low heat. This allows the sugars to slowly come to the surface, and darken gently, rather than on high heat, where the sugars come to the surface quickly, and have a high chance of burning and stinking up your kitchen. I did roast the sooji over a high flame, but that is mainly because I have done it for a long time, and know what to watch for. When you do it at home, you might want to start off at a lower temperature, and maintain the even browning of the grains. Of course, the huge pain in the behind for making uppuma is that you have to stir so darned much! That being said, it is an extremely inexpensive and filling (and very delicious) dish, so it's not like I was complaining about a little stirring. After about fifteen minutes or so of stirring, the sooji transformed colour from a pale blond colour to a much deeper, richer tan colour.
See? Pretty, right? Notice how the colour isn't uniform, but rather graduated, from dark brown, to light tan. This is just perfect for the dish. The reason that we roast the sooji is to cook out the raw cereal taste from it, and to give it a depth of flavour. Once I got it to the colour that I was looking for, I poured it into a waiting stainless steel jug. The reason I do this is because the final step is to pour the sooji into boiling water. If you put it into a bowl, you're going to have to be careful not to spill anything, and you've got the weight of the bowl to contend with. With a jug, you've got a steady stream, no spillage, and very little weight (because mine is stainless steel, as yours ought to be).
In this incarnation, I was looking to inject at least a little bit of healthy stuff. I added in about half a kilo of spinach leaves (roughly chopped) after the onions got fully brown, and allowed the spinach to wilt completely, and to let out a fair bit of its water. Finally, when the vegetables were cooked, I added the water, waited for the boil, stirred in the sooji, and served it!