The Thai couple who run this crammed lunch joint near the corner of Fifth and Jackson discovered the secret to success in their New York restaurants: Use curries made in Thailand, with native lemongrass and galangal, from Grandma’s own recipes. The distinction is evident, particularly in the green curry, which you can augment with crazy-fiery hot sauce (one is labeled “No Kidding”), only if you’re, well, not kidding. Lunchtime finds the joint packed with wage slaves, digging the $5 lunches and sweating out their eye sockets. A takeout window now serves Capitol Hill. For dessert try roti, the panfried flat bread of Thai street culture, drizzled with condensed milk and lavished with whatever sweet toppings are listed on the wall-size chalkboards. Gotta have cash.