Place the onion, the garlic, the mustard seeds, the red pepper flakes, the peppercorns, the ginger, the cinammon, the cloves and the cardamon on a large piece of chessecloth and tie in a little bag. In a large saucepan, combine the spice bag with the vinegar, the molassoes, the soy sauce and the tamarind. Bring to a boil, lower the heat and let simmer for 45 minutes. Mix together the salt, the curry powder, the anchovy and the water. Add to the liquid in the saucepan. Remove from heat. Pour the contents of the saucepan (including the spice bag) into a stainless or glass container. Cover tighly and place in the refrigerator for two weeks, mixing from time to time and squeezing the spice bag. After the two weeks, remove the spice bag and bottle the sauce. Keep in the refrigerator and shake well before use.