No, it doesn’t mean flour that’s been weathered and tested. Simply put, seasoned flour is flour with seasonings added to it. You’ll generally see it as an ingredient in recipes for foods that are first coated in the seasoned flour, then fried or sautéed. The seasonings, which can be as straightforward as salt and pepper or as complex a spice blend as you can create, are incorporated to add additional flavor to the food.
If a recipe calls for seasoned flour, think about what other herbs or spices are present in the dish, and then create your blend by using flavors you think will complement them. If adding spices on the fly seems a little out of your league, play it safe with copious amounts of salt and pepper. Whatever seasonings you add, be sure to add enough so that you can actually taste them. I know, uncooked flour – seasoned or not – is not nearly as taste-inducing as cookie dough or cake batter, but a clean fingertip of flour won’t hurt and you’ll be certain that your flour is adequately seasoned.