My trees' bounty of Thai limes this year made marmalade possible. It is delicious and set to perfection.
Not everyone grows or has access to Thai limes and they do have a unique flavor and fragrance. But this recipe will work for other sour citrus.
You can use any amount of fruit, as long as you stick to the formula below. It's a lot of sugar in the finished marmalade but it is by no means overwhelming - the lime's pith is bitter and needs balance. If you want to use less, begin with half the amount I recommend, stir to dissolve in the lime mixture (before boiling), then taste. If you like it, it will still set, but I think you may stick to my plan! For orange marmalade I’d suggest the same weight of sugar as the fruit's weight. And for grapefruit their weight plus half.
Note: If you do not soak citrus slices before cooking them with sugar the skin can turn hard. Soak the fruit.
Thai Lime Marmalade Formula:
Limes or lemons, weighed, then also measured out in cups after being sliced
Double the cup-amount of water
Double the fruit's weight in sugar
These were my amounts based on my indoor harvest:
13.3 oz (2 ¾ cups, sliced) Thai limes, sliced very thinly
5 ½ cups water
26.6 oz sugar
If you are using your own amount of fruit proceed as follows:
Weigh your limes, and make note of the weight. Slice the fruit very thinly, and pick out any seeds. Measure the fruit in cups. Place the sliced fruit and any escaped juice in a bowl with double the cup-amount of water. Leave to soak 24 hours.
Place the fruit and the soaking water (full of valuable pectin) in a pot large enough that the liquid comes no more than two-thirds of the way up, or it will boil over, later. Bring to a boil for a minute. Turn off the heat and allow to cool completely (this is still helping to soften the skin).
When the mixture is cool again stir in double the fruit’s weight of sugar. Bring to a boil over high heat, stirring until the sugar has dissolved. Insert a sugar thermometer. Keep at a furious boil until the temperature reaches 220’F. Do not be tempted to give up at 118’F, or 119’F. The last few degrees seem to take forever. Be patient.
At 220'F turn the heat off immediately.
If you do not have a thermometer use the spoon test:
Dip a large wooden or metal spoon into the bubbling liquid and then hold it up sideways so the liquid tips out and the length of the spoon is parallel to the pot below. Droplets will at first just rush thinly from the middle of the spoon. As setting point approaches they slow down and when setting point is reached two to three drops form in a more sluggish row along the bottom of the spoon. When they meet in the middle you snatch that pot off the heat.
Off the heat the bubbles will subside. If any white foam or scum is on the surface scoop it off gently. Ladle the hot marmalade into sterilized jars. You can fill all the way but as it sets some of the fruit may rise and set towards the top with bottom just jelly. It still sets perfectly and tastes wonderful. But if you want to distribute the fruit more evenly, fill the jars in three stages, with about 5 minutes between each stage. This way the lower layers will set earlier, trapping their fruit. Don’t wait too long to complete the stages or the marmalade will set in the pan!
Secure the lids tightly.
Enjoy your toast!