Combine pickle ingredients with 100ml water in a saucepan and heat until honey dissolves.
Pour mixture into a bowl to cool then add beetroot leaves to soak for 2 hours.
Preheat oven to 200°C.
Place beetroots on foil, season with salt, pepper, oil, and thyme, then seal into a parcel.
Bake beetroot parcel for 20 to 40 minutes and set aside to cool.
Preheat oven to 180°C and place sea bass on a foil-lined tray.
Cover fish with foil and roast for 10 minutes, then uncover and roast for 10 to 15 more minutes.
Griddle chicory leaves drizzled with oil for 2 to 3 minutes until charred.
Combine chicory, onion, walnuts, and peeled roasted beetroot pieces in a large bowl.
Whisk walnut oil, mustard, and vinegar to create a dressing.
Dress the salad and serve with flaked sea bass and pickled beetroot leaves.