Houston Restaurant Week is halfway over, and it's a great way to go out and try new restaurants that you just haven't found time for in the past year. Lunch is a marvelous way to sample some of the city's better places, like Mark's. It is well worth checking out this year. An interesting menu is particularly inviting at lunch -- $20 for two savory courses. And Mark's is home to an early front-runner for best dish of Restaurant Week: the corn souffle with caviar.