1. Over medium heat, whisk the sugar and red wine vinegar together for several minutes until the sugar dissolves and the liquid turns a dark brown color; add the water to the mixture. Peel and de-seed the plums and slice into 3-4 pieces. Add these to the cooking liquid along with the tamarind sauce, star anise, cinnamon stick, cloves and fish sauce. Simmer for at least 10 minutes until the plums soften and the flavors blend together. Transfer to a food processor and pulse until well-blended. Pass the sauce through a fine sieve; taste and adjust seasoning accordingly (if the sauce is too tart, add a little more sugar).

To cook the duck breasts

1. Pre-heat the oven to 350 F (180 C). Using a sharp knife, score the skin side of the duck breasts, using a criss-cross pattern. Season both sides of the duck with salt and pepper. Place a fry pan on stove top over medium-high heat and add a small amount of oil. Beginning with the skin side, cook each side of the duck breast for 3-4 minutes; the flesh side should be a golden brown color. Wrap each duck breast in foil and cook in the oven for a further 4-5 minutes. The duck will be ready when the meat is a light pink color. If the meat is still red inside, then cook for another few minutes. Remove from oven and let the duck rest for at least 10 minutes in the foil (the meat will continue to cook a little when it rests).
2. Slice the duck breast in long horizontal pieces. To serve, re-heat the sauce, spoon the sauce onto a plate or shallow bowl, then arrange the duck pieces on top of the sauce. To decorate, try adding a star anise piece to the plate or a piece of basil or parsley.