2T mature culture, in regards to JH 'Bread' book.

I suspect that he's looking for a recently refreshed starter. 

I use "Bread" alot and here's what I do (perhaps the purists will cringe, but here goes!)

I always *try* to use a recently refreshed starter.  I also try to take it out of the fridge and let it warm up before using...even if I refreshed it <12 hours earlier (must be noted, I always ensure it's growing well but not yet peaked before putting it into the fridge).

HOWEVER, life happens and I have discovered that if my starter is a bit weary, I can successfully increase the amount of starter that goes into my build and all is OK.  This has come over time and with many attempts.  Thinking about it logically, you are adding a desired number of microorganisms to your build in order to grow it to the state you desire.  The amounts of starter are not so great to affect the hydration of your overall dough, so no worries there.  AND I've found that the bacteria, which are probably higher than desired in this method, do not grow at the same rate as the yeast, so I don't end up with a funky-tasting bread either.  

My philosophy....Know what's best. Then, do the best you can with what you have to work with.

Works for me!

MommaT

All sourdough recipes assume you are using a starter/levain that is viable, that is to say, has a high enough active yeast count.  I'd say that if you haven't fed your starter within 12 hours or so, that at least feeding it once (doubling it) prior to using it won't hurt.  I rarely feed twice before using it and I've been baking with sourdough for 35 years without failure.   At least I can't remember any failures, but that may be a whole different issue :).

You don't have to use much starter when you refresh/feed it however.  You just need to use the right ratio of water/starter/flour.  2 tablespoons of starter isn't much, so I don't think hydration percentage is a big issue for whatever recipe you are looking at.  You could just take out one tablespoon of starter, mix it with 1 tablespoon of water, and add enough flour to make it 'mud like' in consistency (like slightly thick pancake batter).  It'll have a hydration somewhere between 80 and 90 percent.  Weighing such small quantities seems like a waste of time to me, so I wouldn't bother personally.  In any case, you'll end up with slightly more than 2 tablespoons if you follow the instructions that I just gave.  Double it again if you think it needs it.

Brian