How to Make It
In a saucepan, combine the water, sugar, ginger, allspice and vanilla bean and seeds. Add the rhubarb; bring to a boil. Cook over moderate heat, stirring occasionally, until the sauce is jamlike, about 20 minutes. Season with salt and pepper. Discard the vanilla bean.
In a nonstick skillet, heat the oil over moderately high heat. Season the salmon with salt and pepper. Cook, turning once, until lightly browned, 8 minutes. Spoon the sauce onto plates, top with the salmon and pea shoots and serve.