When breading and frying, to which ingredient do I add spices?
The best thing to do is to season the tofu itself (after pressing &amp; drying it).

I'm going to use a bunch of example fried fish recipes here, but the same principles apply to tofu, or frankly anything you coat and fry.

Many recipes for breaded and fried whatever have you season the flour or the batter, and not the item.  This is generally a mistake, because seasoning the flour or the coating means that you have no real control over how much seasoning ends up on each piece, and that the item ends up rather bland (particularly a problem with tofu), and you waste a lot of spices when you throw away the leftover coating.  This is why I almost always use the following procedure:


Dry the item to be fried;
Season it with my seasonings;
Flour, batter, and/or coat it as applicable.


So, why do recipes have you season the flour, batter, or coating?  There's a few reasons for this:


It's traditional (check the back of a box of Zatrain's Fish Fri), and people don't think about what they're doing, they just follow the recipe.
Seasoning the item seems like an extra step in what's already a 4-step process.
The breading is heavy, and they want it to be spicy, not just the contents.


Only the last reason makes any sense.  You can see a good example of thinking about this in this fish recipe, where the author seasons the fish and then seasons the coating as well.  This helps ensure that the thick breading is flavorful as well as the fish.

So, in conclusion: season the item, not the coating, unless the coating is heavy breading, in which case you should season both the item and the breading.