This answer is going to depend a lot on the person you have working for you....
In the past, when he has been forced to make a decision on his own, has it been a good one? Is he generally able to make smart decisions, keeping both the customer and the bottom line in mind? If he is, then your solution is both simple and hard.
Some people get in the habit of asking for help. They either do it because they don't want to get something wrong, you have a habit of always correcting everything they do anyway, or they know that if they ask, you'll give an answer. And for your part, at each situation you probably evaluate it and say - 'if I tell him how to do it, it'll take me 30 seconds, where if I send him out and he screws it up, I could be eating 1/2 a day.' That's the trap that hurts us long term, thinking that giving the answer is the quickest way to go.
Assuming he is a smart, capable person, you need to just send him out into the field. When he says he doesn't have enough information, tell him you trust his judgement and decision making.
I've also told people things like 'Well, then I guess this one's going to be hard for you. Let me know how it turned out.' They usually follow with a look of confusion, then total abandonment. I don't have kids (yet), but would imagine the face looks a lot like when you put your kid on his bike for the first time and tell him to ride. The face you get when he successfully does the job would probably also look a lot like that same child after riding down the block without falling.
Good luck!