Adjust oven rack to middle position and preheat oven to 300°F (150°C).

Place water in a large bowl or measuring cup and sprinkle with gelatin. Let stand until fully hydrated, about 10 minutes.

In a large Dutch oven, heat oil over medium-high heat until shimmering. Season beef all over with salt and pepper and add to Dutch oven. Working in batches, cook steaks, turning occasionally, until beef is well browned on 2 sides, about 10 minutes. Transfer beef to a rimmed baking sheet or large plate and set aside.

Pour off all but 1 tablespoon of oil. Add ginger, star anise, and cassia bark, and sauté until fragrant, about 2 minutes. Add daikon radish and carrots, and cook, stirring occasionally, until vegetables are well-browned, about 4 minutes.

Add chu hou sauce, oyster sauce, light soy sauce, dark soy sauce, and sugar, and cook, using a wooden spoon to stir and scrape up browned bits, until sugar has dissolved, 3 to 5 minutes. Add water and gelatin mixture, stirring to combine.

Cut seared steaks into 2-inch chunks. Add beef and any accumulated juices to the Dutch oven. Stir to combine and return to a simmer over medium heat. Transfer to oven, cover with lid partially open, and cook until beef and vegetables are tender and broth has thickened slightly, about 3 hours. Liquid should hold a slow, steady simmer the entire time; adjust oven temperature as needed during cooking.

Remove stew from oven. Season to taste with salt and pepper. Serve with Chinese greens and rice, if desired.