Preheat oven to 275°F In a blender, combine curry paste, ginger, scallions, garlic and water. Process until smooth and set aside.
In a large Dutch oven, heat vegetable oil over high heat. Season short ribs well with salt and pepper. Whent the oil is smoking, add meat and sear until browned, about 4 minutes on each side.
Pour off and discard oil. Add chicken stock, lemon grass and curry puree to the pot. Bring to a simmer, then cover and move to oven. Cook until short ribs can be easily pulled apart with a fork, 3-4 hours.
Remove meat to a plate. Skim and discard fat from surface of liquid; removed and discard lemongrass. Shred meat with two forks into large (two bite) pieces and return to soup. Place over medium-low heat and add coconut milk, brown sugar, jalapeno, cilantro and lime juice (if you are planning to store any of the leftovers for more than a couple of hours, leave out the lime juice and pass lime wedges at the table). Recover and cook until hot but not boiling, about 5 minutes. Serve with white rice.