Preheat the oven to 220°C, fan 200°C, gas 7. Mix together the tomato ketchup, brown sauce and honey in a small bowl. Set aside.
Cut a few slashes across each chicken thigh. Place on a foil-lined baking tray and brush with the ketchup mixture to coat.
Spread the sweet potato wedges over a separate baking tray, drizzle over the oil, sprinkle with the seasoning and turn to coat evenly. Bake the chicken and the sweet potatoes in the oven for 25 minutes, turning the sweet potatoes once until the chicken is cooked through with no pink remainin and the sweet potatoes are tender.
While the chicken and sweet potatoes are cooking, bring a pan of water to the boil, add the sweetcorn and cook for 6-7 minutes until tender. Drain and serve with the chicken, sweet potato wedges and salad, with a dollop of yogurt on the side.