AFTER Tina Chang puts her 7-month-old son, Roman, to bed, she pads, barefoot, about three feet over to her office, where a desk cohabits with the changing table. She opens the window to take in the sights and sounds of her neighborhood, Park Slope — men arguing on the street, neighbors sipping wine on fire escapes, apartment lights twinkling. She opens a spiral notebook from the 99-cent store and begins scribbling. One night she started with a recipe for black bean sauce, another with the first line of a rejection letter from a literary journal, another with a to-do list.