1. Turn on the oven to 180 degrees C.
2. Use a sharp tool to cut off the tops of the tomatoes where the stems are. Cut them in a circular way at an angle. Squeeze the tomatoes gently over a bowl to remove most of the seeds and extra juice. Put aside.
3. Combine the parsley, scallions, mint, basil, lemon zest, 1 to 2 tablespoons of lemon juice, and salt and pepper in a large bowl. Gradually add the cooked quinoa and mix well.
4. Pack the stuffing into the cavities of the tomatoes with your fingers. Put the tomatoes on parchment paper that has been placed on a baking sheet. Drizzle olive oil over the tomatoes and the stuffing. Put in the oven for 45 minutes to an hour, or until the tomatoes are very soft. It depends on the size of the tomatoes. Take out of the oven and let them cool down.
5. Put on a plate and garnish with basil leaves and a little more olive oil.