Whisk soy sauce, sugar, oil, red pepper flakes, garlic, ginger, star anise, and 1 cup water in large bowl until sugar dissolves. Add short ribs and place a small plate on top of ribs to keep submerged. Cover bowl and chill at least 8 hours and up to 1 day.
2
Preheat oven to 325. Transfer marinade and ribs to a large Dutch oven and bring to a simmer over medium heat. Cover and braise in oven, turning meat once, until ribs are very tender but not quite falling of the bone, 1.5-2 hours.
3
Transfer ribs to a medium bowl and cover with foil to keep warm. Strain braising liquid into medium saucepan; discard solids. Let sit a minute or so to settle and ladle off fat from surface. Bring braising liquid to a boil and cook, whisking occasionally until reduced by half (10-15 minutes).
4
Whisk cornstarch and 3 Tbsp water in a small bowl to make a slurry, then whisk in to reduced braising liquid. Cook over medium, whisking constantly, until glaze is thick and bubbling, about 1 minute. Remove from heat and stir in lime juice.
5
Mound rice in center of shallow bowls and place ribs on top. Drizzle about 2 Tbsp glaze over each. Top with thinly sliced scallion and sesame seeds. Serve with lime wedges and sriracha.
