1 Bring boiling-water canner, half full with water, to simmer. Wash jars and screw bands in hot soapy water; rinse with warm water. Pour boiling water over flat lids in saucepan off the heat. Let stand in hot water until ready to use. Drain jars well before filling.

2 Peel, quarter and finely chop onions. Place in saucepan; add water. Bring to boil. Remove from heat; cool slightly. Place three layers of damp cheesecloth or a jelly bag in large bowl. Pour prepared onions into cheesecloth. Tie cheesecloth closed, hang and let drip into bowl until dripping stops. Press gently. Measure exactly 3 cups juice into 6- or 8-qt. saucepot. (If needed, add up to 1/2 cup water for exact measure.) Stir in vinegar and thyme.

3 Stir pectin into juice in saucepan. Add butter to reduce foaming. Bring mixture to full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring constantly. Stir in sugar. Bring to full rolling boil and boil exactly 1 min., stirring constantly. Remove from heat. Skim off any foam with metal spoon.