According to the online Almanac, there are no vegetables to plant by the moon in December for Region 1 (which the Houston area falls into along with much of Zone 9).
I hope if you have things growing right now that they are doing well. Remember to help protect your plants from the really cold weather. You may have plants you can move into the house where it's warmer or you may have delicate plants in the ground outside that need covering. If you're unsure, look up information online about your specific plant. Enjoy the break from planting in December and check back next month for a few vegetables you can start to plant in January!