It's been Sfuzzi, then Coco Pazzo, and now the newest incarnation of this ever-recycling space is Thunder Grill. It's the latest venture of Ark Restaurants, which also runs Sequoia and America and Center Cafe (the latter two also in Union Station). Thunder Grill is serving up a taste of the Southwest. With a souped-up interior and a selection of some 30 tequilas, Thunder is reminiscent of downtown's Red Sage. Fajitas, enchiladas and quesadillas dominate the offerings, and their fillings run to the unusual, including jalapeno roasted shrimp, portobello mushrooms and spicy chicken hash. Thunder's mid-range entrees (most main dishes are under $15) and variety of Southwest-themed salads and sandwiches (including chili-rubbed salmon and a vegetarian burrito) should keep train travelers and the nearby work crowd satiated. Even if you're not hungry, you should make a stop for one of Thunder Grill's tasty margaritas.