Once this discussion gets going it can be sexy enough to inspire another round; which, with your recently acquired knowledge, is going to be better than the first.
What if she doesn't know?
What happens if you've asked the question but she doesn't have an answer? Keep asking. Don't harass her, obviously, but check in occasionally to see if there's anything different you could be doing to make her feel good. Maybe she's genuinely satisfied, but more likely she's working up the nerve to tell you about her sexual preferences.
If you're in a committed relationship and she's uncomfortable discussing this with you, consider whether there's a problem with your communication in general. For couples that have sex, it's a fundamental part of the relationship and something you should be able to talk about honestly.