Crush the coriander roughly. Mix chicken legs in a bowl with coriander and 1 tablespoon of oil. Season with salt and pepper. Roast the chicken legs in a hot oven at 200 degrees (convection oven not recommended) on a baking tray on the middle shelf for 20 minutes.
Peel the sweet potatoes and asparagus. Cut off the asparagus ends, cut the stems in half crosswise. Cut sweet potatoes in half lengthwise, cut into 2 cm thick slices. Heat 1 tablespoon of oil. Brown the potatoes briefly, salt and pepper them.
Mix the asparagus with 1 tablespoon of oil, salt, pepper and 1 pinch of sugar. Boil up the chicken stock.
Spread the sweet potatoes and asparagus between the chicken legs. Add the chicken stock. Cook for another 15-20 minutes on the middle rack.
Cut the lime into slices. Pluck coriander leaves from stalks. Sprinkle asparagus, chicken and sweet potatoes with chilli flakes and coriander. Serve with slices of lime.