There’s something extremely delightful in peeling an orange to reveal the sweet and sour flesh hidden inside the fruit. It begins with the intensely aromatic essential oils that form a little cloud of scent around you. Then there’s the tingling sensation that erupts on your lips when you taste your first slice of fruit. This sensation is called chemesthesis; it plays a big part in the flavor experience of eating.We deal with the phenomenon of chemesthesis daily: in how we encounter the heat hidden inside a green or red chile, the warmth of a stick of cinnamon, the cooling sensation evoked by mint and green cardamom. When the nerve endings lining the surface of your mouth and lips come into contact with certain chemicals present inside these ingredients, they get irritated and send signals to the brain, which then tells you what’s happening and how to respond, all in a fraction of a second. Over time our brains evolved to interpret this irritation as a pleasurable experience, compelling us to cook with spices, herbs, and ingredients such as oranges and lemons.My Carrot-and-Orange Cake with Sour Cream Glaze celebrates the way oranges trigger our senses. Pay attention and notice your own responses as you scrape the zest from the orange. Rub a piece of zest across your lips and feel your nerves dance in response. The feast for the senses doesn’t end there, of course: the bright sweetness of the juicy oranges marries with the rich orange pigment carotene in the sweet spring carrots. Chopped pieces of dried apricots and candied orange peels give each slice of cake of spot of unexpected fruit sweetness, while the pistachios add texture to the soft cake. Serve it with a cup of warm tea or coffee to complete the experience.