It's basically a simple process. Prepare your mise en place (of course, Indians don't use the French term, but it's the same thing). Deep fry the spices. Fry the aromatics. Fry the veggies. Turn off heat, add fresh aromatics (usually cilantro) and serve.
I found a couple recipes online that repeat this. Eg
http://homecookreceipes.blogspot.com/2009/07/aloo-gobi.html
http://glutenfreebay.blogspot.com/2006/12/aloo-gobi-mattar-potato-cauliflower-and.html
I'm used to having a thicker sauce. I suppose to do that, you simply add some coconut milk. I imagine adding tomato paster with the aromatics would thicken and darken the sauce, too.
Later that night....
So, I cooked the dish. I did the style with no sauce. It came out really well. I made a number of changes.
I used red potatoes instead of russet. That meant less starch in the sauce, thus a less thick sauce. Yes, I know I said no sauce, but the potatoes should leave a thickness. So, I mashed a couple pieces and some peas, thus sort of mimicking the thickness the russets would lend the sauce.
Also, we had additional milk, so my daughter and I made paneer. Paneer is an Indian cheese that's commonly made at home and featured in dishes like Pollack Paneer. Oh, and I didn't have any frozen cauliflower. So, I actually made Aloo Paneer Mattar. Screw cauliflower, anyway.


This is the dish in my cast iron skillet

This is the completed dish