Place a few small plates in the freezer – you'll need them later for testing the marmalade's set.
Roll the oranges on the countertop with light pressure to help release the juice.
Peel the oranges thinly using a vegetable peeler, avoiding the white pith. You’ll need about 25 g of zest.
Juice the oranges until you have around 225 ml of juice.
Slice the zest into fine strips.
Add the orange juice, zest, star anise, cinnamon stick, and cloves to a saucepan. Simmer over medium heat for about 10 minutes.
Remove from heat, stir in the sugar until fully dissolved.
Return the pan to the stove and let the mixture gently simmer, uncovered, for about 45 minutes or until it thickens.
Add the lemon juice and cook for another 2 minutes. To test if it's ready, spoon a little marmalade onto a cold plate and drag your finger through it – if the line stays clear, it's done.
Remove the spices. Pour the hot marmalade into sterilized jars, seal immediately, and let cool completely.