Wash the medlars, cut them into quarters, and remove the pips; take off any imperfections, but no need to peel them.
Pop the medlars in a large pot and add 1 liter water. Bring to the boil; reduce heat and simmer, stirring occasionally to prevent sticking, until the fruit has softened and starts to break up, 30-40 minutes.
Once they have softened, strain the fruit through a fine muslin cloth into a clean bowl for a few hours or overnight. To get the last of the juice, gently press the fruit, but not too hard as you don’t want cloudy jelly.
Once the juice is through, measure it, it should be about 1 liter. Pour the juice back into a clean pot, add the sugar, and bring to the boil over a medium heat, stirring constantly to dissolve the sugar. Once dissolved, continue to cook until it reaches setting point, about 10 minutes. You can tell if it is at the setting point by placing a spoonful of the jelly on a cold plate and letting it cool for 1 minute. Then run your finger through it; if it wrinkles and doesn’t move back, it’s set. If it’s still runny, cook it for a few more minutes and test again. Then add the lemon juice, which adds to the flavour and also helps it set.
Finally, pour the jelly into sterilised jars whilst it’s still hot, seal the jars immediately, and leave them to cool at room temperature. Store the jelly in a cool, dark place for up to a year. Once opened, refrigerate and use within a few weeks.
Recipe by Victoria at https://victoriamag.com/the-countess-of-carnarvon-shares-a-seasonal-recipe/