This recipe is suitable for oranges as well. Wash lemons. Chop off stems, and split lemons in half, and cut into large wedges. Cut off membranes and some part of the flesh as well. Remove seeds. Squeeze out scraps, and sieve. Save juice for later use. Add a couple more lemons in order to readjust the recipe's weight to 750g. To remove its bitterness, lemon needs to be blanched. Place lemon wedges in a saucepan, and cover with tap water, bring to boil and drain. Repeat this step twice, and drain well.
Cover lemons with water and sugar. Bring to boil and cook on low simmer for 3 hours; uncovered. Leave lemons in saucepan, and let stand until it comes to room temperature; best overnight. At this juncture, poached or semi-confit lemons can be canned, or stored refrigerated for months.
In a large vacuum packaging bag, add lemons and sugar. Vacuum seal immediately otherwise lemons will begin to render juice which makes it harder to crayovac; unless you owns a professional grade machine. In a large pot, preheat water first on the stove, and turn off. Set the sous-vide cooking device at 187ºF/86ºC. Immerse bag in hot water and cook for 5 hours. After an hour cooking though, massage the bag to redistribute sugar. Let stand at room temperature for 3 hour prior placing in the refrigerator. Poached lemons can be kept for up to 12 months. Once bag is opened, lemons can be re-vacuumed sealed, or canned, or kept in jar for up to 3 months. The rendered juice from poached lemons can also be used for a lemony simple syrup, sorbet, ice cream, plated dessert inserts... Poached lemons can be used for many pastries such as Lemon-Shaped Dessert, Lemon Ice Cream Tart, Lemon Tart, Ice Creams, Sorbets, and so on...Check these recipes out!
For the cooking and sous-vide method, follow the same protocol. You may want to add a couple blanched lemon wedges, a vanilla bean split in half, or any other spices you like. Note that for the sous-vide method, poach oranges at 191ºF/88ºC for 5 hours.
Lemon confit are more concentrated in sugar and firmer. They are suitable for panettone, king cake topping, fruit confit / Tutti-frutti, coated in tempered chocolate etc... In a large saucepan, throw in prepared lemons with water and sugar. Cook on low simmer for 4 hours. Leave lemon confit in the saucepan, and let stand at room temperature overnight. Store lemon confit in jars with its syrup for up to 12 months. Lemon confit can also be vacuum sealed; drain prior to bagging. Keep refrigerated for more than a year. Save syrup for later use such as brushing out apple turnover, king cake...