Use a paring knife to lift the membrane covering the back of the ribs and pull it off. Cut the ribs between the bones into individual riblets. Pat dry and season lightly with salt.
Heat the vegetable oil in a large Dutch oven. Add the ribs in batches and brown all over, about 3 minutes per batch, Remove to a plate as they brown.
As the ribs brown, combine the brown sugar and 2 tablespoons water in a small saucepan. Simmer over medium-low heat until the mixture darkens to a deep caramel color and is syrupy, 1 to 2 minutes. Add the vinegar, fish sauce, soy sauce and sriracha. Stir until smooth. Remove from the heat and stir in the ginger and garlic.
Once all of the ribs are out of the pot, add the brown sugar sauce and coconut water and bring to a simmer. Nestle the ribs in the sauce, bring to a simmer and cover. Cook until the ribs are tender but not falling apart, about 1 hour.
Uncover the pot, increase the heat and reduce the sauce, turning the ribs to coat all sides, until it is thick and syrupy and glazes the ribs, 3 to 4 minutes. (Stir the bottom of the pot too so the sauce doesn’t burn.) Pile the ribs on a platter and sprinkle with the scallions and jalapeno.