Rennet is the term used for a complex of enzymes found in the stomach of mammals and used to digest milk. Traditional rennet is sourced from the stomach lining of dead, milk-fed calves and is used extensively to coagulate or curdle the milk when making cheese. Due to animal welfare concerns and the limited availability of traditional rennet, other methods of production have been discovered. Specially modified bacteria produce similar enzymes, and extracts from certain plants and vegetables have coagulating properties.
Put on rubber gloves to protect hands from the stinging nettles.
Place nettles in colander, and wash carefully under cold water.
Pour the stinging nettles into the saucepan, and cover with the water.
Add the salt to the saucepan, and place on the stove over high heat.
Cover the pan once the water has come to a boil, and lower the heat to medium-low.
Simmer the nettles in the salt water solution for 20 minutes, stirring carefully with the wooden spoon when necessary.
Line the colander with the cheesecloth, and place inside the large bowl.
Pour the water and nettle mixture carefully through the cheesecloth and colander, allowing the liquid the flow into the bowl.
Let cool for 5 minutes, then fold the sides of the cheesecloth over the nettles, squeezing carefully to extract any remaining liquid, and dispose of the nettles and cheesecloth.
Pour the cooled liquid into an airtight container, cover and fridge for up to one week.
237 ml (1 cup) of this vegetable rennet will curdle approximate 4 litres (4 quarts) of milk.