Bring a large pot of water to a boil over high heat. Blanch the grape leaves in the boiling water for 10 minutes, drain and set aside.
In the same pot, place the brown rice, olive oil, sea salt, onion and garlic over medium heat. Stir well and cook for 15 minutes, stirring intermittently, or until the rice is browned and the onions are soft.
Mix the parsley, mint and tomato paste into the pot, followed by the vegetable broth, and lemon juice. Allow rice mixture to cook for about 25-30 minutes, or until most of the liquid is absorbed and the rice is tender, but not fully cooked. If not enough liquid add some boiled water while still cooking.
Add the chopped chickpeas and diced tomatoes to the rice mixture. Season with the cumin and salt to taste.
Place a grape leaf flat on a plate. Put about 2 tablespoons of filling in the center of the leaf and roll into a bundle. Repeat until you are out of leaves and filling.
Place all the stuffed grape leaves into a pot and pour vinegar and enough fresh water in to cover the bundles.
Place the pot on the stove over medium-high heat and bring back to a boil. Turn the heat down and simmer for an additional 15 minutes, or until the rice filling is fully cooked.