Combine garlic & vinegar in a 2 litre kettle. Simmer mixture gently, uncovered, over medium heat for 15 minutes.
Remove pan from heat & pour mixture into a 1 litre glass jar. Cover & let stand at room temperature for 24-36 hours.
Pour flavored vinegar through a wire strainer into a bowl, pressing the garlic with the back of a spoon to squeeze out liquid. Discard any residue. Measure the liquid & add vinegar, if needed, to make 1 cup.
Measure sugar into a dry bowl. Combine the garlic-vinegar solution & the water in a 5 or 6 litre kettle. Add pectin, stirring well.
Over high heat, bring mixture to boil, stirring constantly to avoid scorching. Add sugar, & stir well. Bring mixture to a full, rolling boil. Add butter to reduce foaming. Continue stirring. Boil the mixture hard for exactly 2 minutes.
Remove pan from heat & skim off any foam. Add red, yellow or orange food coloring if desired. Pour jelly into prepared glasses. Seal according to directions on recipe folder in pectin package.
Makes approximately 5 cups.