A sweet potato, when baked, is the ultimate comfort food. Its soft, yielding texture and slight sweetness is countered here by the tangy crunch of the Middle Eastern spice mix, za’atar. You can buy ready-made za’atar, but it’s easy to make your own and it is worth experimenting with different blends of herbs and spices. If you are unfamiliar with the spice sumac, this ground deep pinky-red berry has a slightly tart, lemony flavour and, like shop-bought za’atar, can be found in larger supermarkets, in Middle Eastern grocers or online. Keep a jar for when you want to liven up yogurt, humous, eggs, soups and salads or whatever takes your fancy.