Rinse grape leaves in cold water. Remove remaining “stems” from leaves. Place leaves in a colander to drain while preparing the filling.
Season the fish and cut into chunks; roll the leaves. Line the pot with the onions and tomatoes and herbs and stack with the stuffed grape leaves.
Add 2 cups of water, the juice of the lemons and the olive oil; hold the stuffed leaves tight with a smaller plate. Bring to a gentle simmer, covering the pot; let the mixture bubble up for 40 minutes very gently; uncover. Cool a bit, taste and adjust seasoning. Serve at room temperature or slightly warm with additional lemon quarters.