Some very good ideas have been posted already, including simply enjoying the strawberries with your sub.

There are so many possibilities with this, though.

Bound and blindfolded you can play with your subs senses and the pleasure derived from your treat. Take a bite of the tip of the strawberry and gently rub it under his nose so that his sense of smell is invaded with it. Then tell him to pucker his lips, after which you rub the open end of the strawberry on his lips, finishing by barely pushing it in his mouth then quickly withdrawing. leaving the taste and temptation but not the actual treat. You could also replace it with something bitter the next time.

meh, a few more ideas, fwiw.