- Remove the stem base of each orange.
- In a saucepan, tightly fit the oranges side by side. Cover with water, about 3/4 inch (2 cm) above the oranges.
- Bring to a boil, cover and let simmer over low heat for 30 minutes. With a slotted spoon, remove the oranges and set aside on a plate. Let the oranges cool. Set aside the cooking water.
- Cut the oranges in half. With a spoon, remove the flesh. Set aside the peels. In a blender, process the orange flesh with 1 cup (210 g) of the sugar. Pour into the same saucepan. Add 1 cup (250 ml) of the reserved cooking water.
- Bring to a boil and let simmer for 10 minutes. Strain, pressing the mixture to extract a maximum of liquid. Set aside the strained orange syrup and discard the pulp.
- Meanwhile, thinly julienne the peels, and cut them into 3 pieces. Place in the saucepan.
- Add the orange syrup, the remaining sugar (2 cups / 420 g), the lemon zest and 2 cups (500 ml) of the reserved cooking water.
- Bring to a boil and let simmer for 1 hour or until a candy thermometer reads 223°F (106°C). Skim several times while cooking.
- Transfer into airtight containers or hot jars. To sterilize jars of marmalade, completely cover with water and boil for 10 minutes. Sterilized jars will keep for 1 year at room temperature. Unsterilized jars will keep for 1 month in the refrigerator.
During our tests, we loved working with navel oranges—medium-sized with sweet and oftentimes seedless flesh.