Different cooking methods produce different results, it's not just about onions. But the maillard reaction comes from frying them, theres also a textural element to the difference. Using fat promotes allows browing and even caramelization.
Try using less fat to fry them instead of 0 fat. If you're talking about deep frying, then try the microwave method from americas test kitchen.
(Im not a 100% sure I'm right but i'm fairly confident)
No, but you can boil/steam to extract flavor before frying. I do this when I make fried potatoes, and a lot of other things. I start the potatoes off in a bit of water with the alliums, butter, and spices added. I cover it loosely, and once the water boils off, the potatoes start frying.
This accomplishes a couple things. First, it keeps the potatoes from ending up hard (not raw, but hard), because the water draws some starch out and hydrates the potatoes. Second, it extracts the flavor from the allium (I favor shallots) and spices, mixing with the starch that ends up coating and browning. The starch being pulled out of the potatoes, but being left to coat them, also makes the end product more cohesive, with shallots clinging better to the potatoes.
@SubArcticTundra Because the flavor goes into the water! That's why soup broth tastes good. Try chopping up half an onion, boiling for 10 minutes in a pot with enough water to cover them, then taste the water.
I think they mean pan streaming. And the difference is the flavor that is leached by the water will be limited, or the left over water would be used in a sauce.
Are you putting the onions in the water when steaming them, or are they properly elevated so that the rising steam is cooking them? Because, generally, boiling things or cooking them in water directly kinda mutes the flavor.
Instead of sauteing with water, use butter. Or nothing if you are confident they won't stick to the pan. Also a sprinkling of salt helps draw the moisture already in the food out and helps give it a crust.