Use a wide, shallow saucepan which will take the shallots in one layer, then simply place all the above ingredients except the sugar in it and bring everything up to simmering point. Then turn the heat down to its lowest setting and let the shallots simmer (just a few bubbles breaking the surface) for 1-1¼ hours. Turn the shallots over at half-time, and 10 minutes before the end of the cooking time sprinkle in the sugar. You should end up with tender shallots glistening with a lovely glaze. If your heat source is not low enough, you may need to use a diffuser. If it's more convenient you can cook the shallots in advance, and gently re-heat them before serving.