Instructions

Place 2 small plates in freezer to chill. Wash and dry four 1-cup jars. Set canning rack in large pot, place the four 1-cup jars in rack, and add water to cover by 1 inch. Bring to simmer over medium heat, then turn off heat and cover to keep hot.
Bring all ingredients to boil in Dutch oven over medium-high heat, stirring often. Once sugar is completely dissolved, boil mixture, stirring and adjusting heat as needed, until thickened and mixture registers 217 to 220 degrees, 10 to 15 minutes. Remove pot from heat.
To test consistency, place 1 teaspoon jam on chilled plate and freeze for 2 minutes. Drag your finger through jam on plate; jam has correct consistency when your finger leaves distinct trail. If jam is runny, return pot to heat and simmer 1 to 3 minutes longer before retesting. Skim any foam from surface of jam using spoon.
Place dish towel flat on counter. Using jar lifter, remove jars from pot, draining water back into pot. Place jars upside down on towel and let dry for 1 minute. Using funnel and ladle, portion hot jam into hot jars, leaving ¼ inch headspace. Slide wooden skewer along inside edge of jar and drag upward to remove air bubbles.
For short-term storage: Let jam cool to room temperature, cover, and refrigerate until jam is set, 12 to 24 hours. (Jam can be refrigerated for up to 2 months.)For long-term storage: While jars are hot, wipe rims clean, add lids, and screw on rings until fingertip-tight; do not overtighten. Return pot of water with canning rack to boil. Lower jars into water, cover, bring water back to boil, then start timer. Cooking time will depend on your altitude: Boil 10 minutes for up to 1,000 feet, 15 minutes for 1,001 to 3,000 feet, 20 minutes for 3,001 to 6,000 feet, or 25 minutes for 6,001 to 8,000 feet. Turn off heat and let jars sit in pot for 5 minutes. Remove jars from pot and let cool for 24 hours. Remove rings, check seal, and clean rims. (Sealed jars can be stored for up to 1 year.)