Heat the oven to 200C/fan 180C/gas 6. Put the sweet potatoes and red onions onto a large baking tray and drizzle with a generous glug of oil. Season, then roast, turning halfway, for 40-45 minutes or until tender but not mushy.
Meanwhile, mix together the dressing ingredients. Put the chicken on a separate baking tray with the chopped prosciutto. Drizzle 2 tsp of the dressing on top of each chicken breast and add to the oven for the final 10-15 minutes with the sweet potatoes.
Heat the grill to high. Grill the chicken for 3-4 minutes or until the skin is golden.
Put the kale in a large mixing bowl with the olive oil and plenty of seasoning. Pour over the lemon juice and mix in the carrot and 1/2 the pomegranate seeds.
Arrange the kale salad on a platter with the potatoes and onions. Slice the chicken and avocado, and add to the platter. Drizzle over the dressing and scatter over the rest of the pomegranate seeds. Eat straight away.