Homemade orange marmalade needs only citrus, water, sugar, and patient cooking. This tested no-pectin method keeps fine strips of peel suspended in a bright, softly set preserve.
The quantities below make about seven to eight 240 ml (half-pint) jars. For shelf storage, follow the water-bath processing step exactly.
Rinse the fruit thoroughly. Cut the peel into strips about 3 mm wide; the attached white pith supplies natural pectin. Combine the measured peel, pulp, lemon, and water in a large, deep pot.
Bring to a boil, then cook over medium heat for about 1 hour, stirring occasionally, until the peel is tender.
Add the sugar gradually and stir until completely dissolved. Bring the mixture to a rapid boil and cook for about 45 minutes, stirring more often as it thickens.
Test a small spoonful on a chilled plate. After 30 seconds, push it gently: the surface should wrinkle and the syrup should not run like water. Remove the pot from the heat promptly to avoid a stiff, gummy set.
Ladle into hot, sterilized half-pint jars, leaving 6 mm (1/4 inch) headspace. Apply prepared lids and process in a boiling-water canner for 5 minutes at 0-1,000 feet, 10 minutes at 1,001-6,000 feet, or 15 minutes above 6,000 feet. If jars were not pre-sterilized, increase those times to 10, 15, and 20 minutes.
Let the jars cool undisturbed for 12 to 24 hours, then check the seals. Refrigerate any unsealed jar and every jar after opening. The finished marmalade should taste bright, pleasantly bitter, and clean rather than overly cooked.