Wash the lemon and 1 orange thoroughly and cut the peel into fine strips with a julienne shredder. Halve the lemon and oranges and squeeze (approx. 850 ml). Wash the carambola, dab dry and cut into thin slices.
Mix the orange juice and zest, Campari, jam sugar and starfruit well in a pot. Bring to the boil over a high heat, stirring constantly, and let it boil for 1 minute until it becomes bubbly. Fill jam hot into clean glasses and close them immediately.
Place on the lid for about 5 minutes. Makes 4-5 glasses.