Dinner & BFast walking Dist. Union Station?
La Noche Buena is the best I've found on Olvera Street. They serve breakfast, lunch, and dinner. Very reasonable, spicy...especially with their home-made table salsa. Tiny place but they have waiter service at the tables.
Can't go wrong with Phillipe's. Had lunch there yesterday and still good. The mustard is very spicy, although the health department made 'em get rid of the table top jars with the spoons. Now they use squeeze bottles.
You could walk to Little Tokyo with dozens of good restaurants there. Best route at night would be to cross over from the station towards Olvera St. and walk three blocks down Los Angeles Street to 1st St. and turn left.
Good breakfasts just across the street at Philippe's, one of L.A.'s oldest restaurants. You can walk to anyplace in Chinatown although the Chinese restaurants are just ok, and not particularly cheap or spicy. People seem to like Mayflower and Hop Li, I like Full House Seafood which is open quite late.
Mexican restaurants at Olvera St. are also close, but probably closed after 9 pm and very touristy.
Here's a good post on nearby restaurants:
Philippe the Original
1001 N Alameda St, Los Angeles, CA 90012
Full House Seafood Restaurant
963 N Hill St, Los Angeles, CA 90012
Hop Li Seafood
526 Alpine St, Los Angeles, CA 90012
685 N Spring St, Los Angeles, CA