Soak the grape leaves for 10 minutes, in plenty of water with 2 tablespoons of red wine vinegar added to it. Then transfer leaves to a strainer.
Fill a large cooking pot or stock pot with water and bring to a boil. Add 3 tablespoons of red wine vinegar. Once the water comes to a boil add the leaves and cook for 2 minutes from the moment the water starts to boil again.
Using a slotted spoon, transfer the leaves to a very large pot filled with very cold water. Let the leaves cool completely. Then transfer leaves to a strainer in stacks of 10 or 15 leaves. With the bottoms right on top of the other.
Take one stack of the leaves and gently squeeze them inside the palms of your hands to release any leftover water. Then place the stack on your working surface with the wrong side of the leaves facing upwards. Roll them tightly and place them inside the jar.
Repeat this process for the remaining stacks of leaves.
In a measuring cup add the remaining 1 tablespoon of red wine vinegar, kosher salt, and lemon juice. Add 200 ml of hot boiling water and mix well until salt dissolves. Then pour this brine into the jar with the leaves. Make sure you leave some space on top so it won't touch the jar's lid. NOTE: If you're using a larger jar and the brine isn't enough, just make another batch or half a batch of it. Always keeping the same salt-acid ratio.
With a spoon press the leaves to sink under the brine. Then add a thin layer of olive oil on top to float on the surface and act as a protecting shield against microorganisms. Close the jar and keep it inside a dark cupboard for up to a year.