If you can access fresh vine leaves, wash them first and boil them in the water for 3 minutes to soften. Drain leaves and put them aside.
But if you want jar leaves, rinse the grape leaves under cold water to remove any brine or excess salt.
To prepare the filling of the Koupepia, saute the onion in a pan with olive oil on low heat for 5 minutes until they become golden.
After that, pour minced meat into the same pan until they become well roasted, then remove the pan from the heat.
Combine the roasted meat, rice, onion, garlic, parsley, mint, olive oil, tomato paste, lemon juice, salt, and pepper in a large mixing bowl. Mix well until all the ingredients are evenly incorporated.
Before filling the leaves with ingredients, place some large leaves on the bottom of the pot to avoid sticking.
Fold the sides of the leaf over the filling, then roll it tightly from the stem end to the tip, forming a compact roll.
Repeat this process for wrapping the rest of the grape leaves and filling.
Arrange the stuffed grape leaves in layers, seam side down, in the pot, and pour enough water to cover the grape leaves.
Place a heavy lid on the grape leaves to keep them from unravelling during cooking.
Bring the water to a simmer, then reduce the heat to low and simmer for 1-2 hours, or until the rice is cooked and the flavours have blended.