Cape gooseberries have many names, including physalis and ground cherries. They are grown in South America (although were originally grown in South Africa) and are available here all year. I tend to buy them in the winter, when there is not so much choice of fruit for sauces. They make a pretty garnish with their papery brown cloak and they cook very well too. If you can't find cape gooseberries, you can substitute one small mandarin orange, thinly sliced with its peel. Add to the pan along with the onions. Serve with quinoa and sautéed dandelion greens.