Combine the ingredients in a preserving kettle. Stir well. Bring to the boil, stirring frequently, over high heat. Adjust the heat so that the relish bubbles moderately vigorously; stir frequently and remove any scum.
When the relish is a rich brown colour and has the smooth, thick consistency of jam, it is ready this happens after about 40 to 60 minutes.
Fill hot sterilized canning jars. Drop clean, new canning jar lids into boiling water and leave them there, off the heat, to allow the circle of sealing compound to soften. When filling each jar with jam, jelly or relish, leave a 1/8 inch headspace. Immediately screw the lid on tightly, then flip the jar over and back again. Set to cool on a rack. When the jam has cooled, check the seal to make sure the lid on the jar has concaved. If it has not, refrigerate the contents and use within a month.
Another method is--Pour jam or jelly or relish into hot, clean jars, leaving a ¼ inch headspace. Wipe the edge of the jar with a clean damp cloth. Set the jar lids, previously softened in boiling water as described above, on the jars and tighten. Set on a rack in a canner, sometimes called a boiling water bath. Fill with water to a level 1 inch above the top of the jars. Cover the canner, bring to the boil over high heat and boil hard for 15 minutes. Remove the jars, cool on a rack and check the seals. Yields five 8 oz. jars.