I don't believe this is a good analogy. The amount of sugars in an onion is definitely not the same as in a seed of the cilantro plant for example. So the react

I don't believe this is a good analogy. The amount of sugars in an onion is definitely not the same as in a seed of the cilantro plant for example. So the reactants would be different and so would be the product. This is evident by the amount of time needed for cooking, where to caramelize an onion takes a relatively long time. I think toasting spices can vaguely round out flavors, but doesn't really bring about a dramatic change.