Wash the citrus thoroughly before peeling, then cut the peels into your desired shape (matchsticks, diced, or peel the fruit with a vegetable peeler to get thin strips) and place in a saucepan and cover with water.
Bring to a full boil for about 2 minutes then drain. Repeat 2 more times, always starting with cold water.
The last time you drain the peels, leave them in the sieve and set aside while you make the syrup in the saucepan.
Combine the water, sugar and salt in the saucepan and heat on medium, whisking occasionally, until the sugar has fully dissolved.
Add in the peels and let simmer, uncovererd, on low for around 30 minutes. They’ll become more and more translucent and soft. If you’re using a more bitter peel like lemon, you can let them simmer longer. It’s also a matter of preference, so taste as you go.
Once they’ve candied, you can transfer them with the syrup into a container, let them cool, then close and store in the fridge. Or you can strain them well (keep the syrup, it’s great for cocktails and cakes!)and roll in sugar or dip in chocolate and let them dry sligthly on a tray or wire rack at room temperature for up to a day before storing in a closed container.