Pre-heat the oven to 200° C.
Heat the sunflower oil in a ovenproof saute pan over a medium-high heat. Season the chicken legs and sear until golden all over. Move to the oven and roast for 30-35 minutes.
Meanwhile, heat the vegetable oil in a heavy based saucepan to 170° C. Bring a pan of salted water to the boil and blanch the cauliflower for 2 minutes. Remove and refresh under cold running water for a further 2 minutes. Drain and set to one side. Blanch the green beans for 2-3 minutes in the same water and refresh in cold water. Set to one side.
Prepare the batter by beating the egg in a mixing bowl and adding the water to it. Gently mix in the flour using a fork being careful to not overwork the batter. Dip the cauliflower in the batter and then straight into the vegetable oil. Deep-fry for 2 minutes until crispy and golden and remove to kitchen paper to drain. Keep warm to one side.
Check the chicken and remove if cooked (the juices will run clear when the legs are cooked). Rest in a warm place. Melt the butter in a saute pan over a medium-high heat and toss the green beans in it until heated through. Season.
Arrange the legs on plates with the cauliflower, green beans beside and a little chopped thyme on top.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.