To make the short ribs: Preheat the oven to 300°F (150°C). Season each short rib with salt and black pepper.
In a large Dutch oven or oven-safe pot, heat the oil over medium-high heat. Add the short ribs, working in batches to avoid overcrowding, and sear on all sides until browned. Transfer to a plate. Remove any excess fat from the pot and discard it.
Add the onion to the same pot and cook, stirring often, until softened and translucent, 5 to 7 minutes.
While the onion cooks, combine the ketchup, pomegranate molasses, soy sauce, garlic, lemon juice, cumin, and paprika with 1 cup (240 ml) of water in a medium bowl and mix well. Pour this mixture into the pot with the onion and bring to a simmer. Taste and adjust for salt if necessary.
Place the short ribs back into the pot and stir to coat the ribs in the onions and sauce. Cover with the lid or aluminum foil, and bake for 3 hours, or until fork-tender, then uncover and return to the oven for another 10 to 15 minutes to brown the tops.
Transfer the short ribs to a serving dish. Remove excess fat from the pot by scooping it out or layering a paper towel on top to absorb it, then discard.
Let the sauce in the pot simmer for 10 to 15 minutes, until thickened, then brush it on top of the short ribs and serve the rest on the side.
Garnish with microgreens or fresh parsley and mint and pomegranate arils.