Heat the oven
Preheat the oven to 180°C.
Browned hard, braised in onion-soup broth, and finished in a gravy built in the same pan. The only way to get them wrong is to stop cooking too early.
Braise ahead, finish later
The first braise and the gravy both hold well. Cook to the point where the ribs are just tender, cool them in the broth, and do the last hour on the day.
Preheat the oven to 180°C.
Liberally season the tops and sides of the short ribs with the seasoning salt, pepper and granulated onion. There is no need to season the back where the bone is.
Place a large skillet over medium-high heat and warm the vegetable oil. When the oil is shimmering, add the short ribs in batches, meat-side down, and cook until browned. Then turn them bone-side down and brown for two minutes more.
Transfer the short ribs to the roasting pan in a single layer, leaving the fat behind in the skillet. When all the ribs are in the pan, remove the skillet from the heat and reserve it — that fat is the base of the gravy. Top the ribs evenly with the whole garlic cloves and a little of the chopped onion, keeping the rest of the onion back.
In a medium saucepan over high heat, combine the cold water and one packet of the soup mix. Whisk thoroughly to combine and bring to a simmer, then remove from the heat and pour it over the short ribs — using just enough liquid to partially submerge them. Cover the pan with a lid or foil, transfer it to the oven, and cook until the ribs are just tender.
Meanwhile, return the skillet with the fat to medium-low heat. Add the chopped garlic and the onion you kept back and stir to combine. Add the bouillon powder, the second packet of soup mix and the browning sauce, and stir well. Add the flour and whisk constantly until it is nice and toasted.
Add most of the warm water, a little at a time, whisking constantly. Then whisk in more warm water as needed for a medium gravy consistency. Bring to a bare simmer and continue simmering, stirring occasionally. Remove this gravy from the heat and set it aside while the short ribs carry on cooking.
When the short ribs are ready, transfer them to a platter or bowl, leaving the broth in the pan. Add the gravy to the broth, a cup or so at a time, whisking to mix well — use only as much of the gravy as you need to reach a medium-thick consistency. Return the short ribs, meat-side down, to the roasting pan. Re-cover with the lid or foil, return to the oven, and cook until they are completely tender.
Serve the short ribs immediately, with rice or mashed potatoes and plenty of the gravy.