How do I speed up ripening?

The answer

Place the fruit in a loosely closed paper bag at room temperature, perhaps with a ripe banana, and check it daily. The bag traps the ethylene gas that ripening fruit gives off, and a ripe banana or apple releases plenty of it. This works for climacteric fruit such as bananas, mangoes, peaches and pears, but not for lemons or pineapples, which will not become sweeter. Avoid sealed plastic bags and direct sun, which encourage mold.