Trim the onions and remove the root and the stem, peel them. Slice the onions horizontally into ½ inch thick rings. Separate the larger easily separable ones. Keep the smaller pieces to use in a curry.
Now transfer these rings to a steamer and steam over rapidly boiling water for 3-4 minutes.
Meanwhile preheat oven to 200° C/ 400° F.
Rinse the onion rings in cold water to stop them from cooking further. Drain and wrap them in a tea towel for a few minutes.
Set your baking tray up by lining it with a foil, parchment or a Silpat. If using a foil or parchment grease it with a few drops of oil. Mix the rawa with salt, herbs and chilli powder whisk well.
Beat the egg whites and dip the onion rings in the bowl. Toss and coat them well.
Now dip them in the rawa mixture and toss to coat well. Place the coated ring on the baking tray. Repeat with the next slice. See that the rings do not overlap.
Bake the onion rings in a preheated oven for 15-18 minutes or the edges do turn nice and golden. Watch the rings as they tend to burn if they bake too long or are thinly cut.
I let the rings sit in the oven for about 10 minutes. Remove and serve immediately.
Notes
In case you are using flour, you will have to flip the rings over and bake them again. You will also have to spray them oil before you bake them and when you flip them.