Use an organic lemon and orange if possible, since the skin is also used in the marmalade. This recipe is from The Canadian Farm Cookbook, circa 1911
1 orange (use a Seville orange in winter when available)
2 c. water
2 c. grated carrot
2 ½ c. sugar
Scrub the lemon and orange and shred the zest on a box grater. Finely chop the fruit. Pick out the seeds and put them into a tea ball or scrap of cheesecloth.
In a large pot, combine the lemon and orange zest, the chopped fruit, the seeds and the water, bring to a boil over medium-high heat, and boil for about 10 minutes. (The seeds are rich in pectin, which is why they are cooked along with the fruit.) Add the carrots and sugar and boil gently for 30 minutes longer, until the marmalade is thick and forms a sheet when poured from a spoon. Pull out the seeds and process the marmalade in jars according to the manufacturer’s directions. Makes three 8 ounce jars.