Generously season ribs on one side with salt and pepper; set aside.
In a Dutch oven over medium-high heat, add oil and when shimmering, working in batches, add seasoned short ribs seasoned side down; season the top generously with salt and pepper.
Cook until browned, about 2 minutes per side. Remove and set aside.
Preheat oven to 325ºF
Reduce heat to medium, add onion and sauté for 2 minutes, scraping the bottom of the pot to dislodge any brown bits.
Add garlic and ginger; sauté for 1 minute.
Pour in Shaoxing wine, stir well and if there’s still brown bits at the bottom of the pot, scape them off.
Add 2 cups of beef broth, brown sugar, sweet chili sauce, soy sauce, hoisin sauce, and sriracha. Quickly stir and add lemongrass.
Turn heat back to medium-high. When it gets there, return the ribs including any accumulated juices. Add 2 more cups beef broth.
When it starts boiling, cover and transfer to preheated oven and braise for 1 ½ to 2 hours.
Halfway through cooking, flip the top short ribs over and spoon some liquid on top; return for the remaining cooking time.
When ribs are fork-tender and the internal temperature reaches 170ºF, remove from the heat and transfer short ribs to a plate; set them aside.
Remove the lemongrass and discard it.
Turn the heat on medium-high and bring the mixture to a boil.
When it gets there, add cornstarch mixture and stir until the sauce thickens, about 45 to 60 seconds; taste and adjust if necessary.
Return the beef short ribs back to the Dutch oven including any accumulated juices, reduce the heat to medium-low, push them down into the sauce keep them warm until ready to serve.