Sweet potato chips with onions and peas

Peel sweet potatoes and cut into long, chunky fingers. Toss in olive oil and bake for 10 minutes. Toss onion in olive oil and scatter over the sweet potato. Bake for a further 15 minutes or until sweet potato is tender and onion rings are browned. Drop peas into simmering salted water, bring back to the boil and drain. Toss in butter, sea salt and pepper. Pile sweet potatoes on a warm serving plate, tip peas over the top, scatter with onions and sage leaves and serve.