Preheat oven to 200 degrees C. Spray a 22cm x 32cm baking dish with cooking spray.
Spread beetroot, white potatoes, turnips, carrots, sweet potato and red potatoes in a single layer in the baking tray. Drizzle 2 tablespoons olive oil on top. Squeeze lemon juice over vegetables and season with rosemary, thyme, coriander, cayenne, salt and pepper.
Bake in the preheated oven until root vegetables are just tender, about 45 minutes.
Heat remaining 2 tablespoons olive oil in a frying pan over high heat when root vegetables are nearly done. Cook and stir garlic over medium heat until fragrant, about 1 minute. Add kale; cook and stir until bright green, about 5 minutes. Season with sea salt and mix into the root vegetables.