Preheat OvenPreheat your oven to 350°F (175°C).
Prepare the SauceIn a bowl, whisk together the chili garlic sauce, sesame oil, soy sauce, brown sugar, and rice vinegar. Set aside.
Coat the RibsLightly toss the boneless beef short ribs in flour until evenly coated.
Sear the RibsHeat 1½ tablespoons olive oil in a Dutch oven over medium-high heat. Sear half of the ribs for about 3–4 minutes per side until browned. Repeat with the remaining ribs using another 1½ tablespoons of olive oil. Season both batches with salt and pepper.
Sauté the AromaticsLower the heat to medium. Add garlic, scallions (or onion), and grated ginger to the Dutch oven. Sauté for 2–3 minutes until fragrant.
Build the BraiseReturn the seared ribs to the pot. Pour in the prepared sauce and 1 cup of beef broth. Stir to combine, ensuring the ribs are mostly submerged.
Oven-BraiseCover the Dutch oven and transfer it to the oven. Bake for 1 hour. After the first hour, pour in the remaining 1 cup of beef broth, cover again, and continue baking for another hour. Then uncover and bake for an additional 30 minutes.
ServeWhen the ribs are fork-tender and the sauce has thickened slightly, remove from the oven. Serve hot with rice or mashed potatoes. Garnish with chopped scallions, sesame seeds, or a squeeze of lime if desired.