Prepare the Yogurt Base: In a medium mixing bowl, combine the chilled Greek yogurt, ground flaxseed, and fresh lemon zest. Whisk thoroughly until the mixture is smooth. Let this base rest in the refrigerator for at least 10 minutes to allow the flaxseed to hydrate and thicken the yogurt.
Toast the Walnuts: Place the raw walnut halves in a small, dry skillet over medium heat. Toast for 4-5 minutes, tossing frequently, until they become fragrant and deepen slightly in color. Immediately remove from the heat and set aside to cool. Once cooled, roughly chop them.
Prepare the Berries: In a separate small bowl, gently combine the mixed fresh berries with the honey. Stir carefully to coat the fruit without crushing it. Allow the berries to sit for 5 minutes to create a light, natural syrup.
Assemble the Bowls: Remove the yogurt base from the refrigerator and give it one final stir. Divide the yogurt evenly among your six serving bowls.
Add the Toppings: Spoon the honey-berry mixture over the center of the yogurt in each bowl. Distribute the toasted, chopped walnuts evenly over the top.
Garnish and Serve: Sprinkle the ground cardamom over the dish, then delicately drizzle with the extra virgin olive oil. Serve immediately and enjoy.