True yams, which originated in Africa and Asia, are starchy, dry tubers rarely seen in U.S. markets. What Americans call yams are actually sweet potatoes, which you can buy in light yellow-, white- and orange-fleshed varieties. These American "yam" sweet potatoes need herbs and spices that balance the sweetness and creaminess of the vegetable, such as those with bright acidity, heat, touches of bitterness or complementary sweet overtones. Always add a sprinkling of salt along with the spices and herbs to bring out the flavor of yams and to offset their sweetness.
Hot and Spicy
Spices such as cayenne, curry, smoked paprika, pepper, mustard and chili powder contrast with the sweetness of yam sweet potatoes and deepen their flavors. Sprinkle grilled or roasted yams with the spices before roasting them, or make a hot mustard sauce to drizzle over them after cooking. For a spicy yam sweet potato salad similar to German potato salad, toss cool, steamed yams with a mustard sauce using powdered and grainy mustard for a textural contrast with the creamy yams.
Fresh Citrus Flavors
Citrus zest in a dry spice blend brings acidity to a yam sweet potato dish and keeps the vegetable from becoming cloyingly sweet. Add lemon, lime or orange zest blends directly to a cool yam salad just before serving or to an Asian soup with yam chunks and shrimp. Or simply add the zest to a yam side dish tossed with butter and herbs, along with a bit of juice from the fruit you choose.
A Dash of Bitter
Most herbs, whether intense or delicate, have a hint of bitterness along with their particular flavor. Like acidity, the bitterness balances a yam's sweetness. Use dry herbs at the beginning of cooking, where they can soften and release their flavors, and fresh herbs sprinkled on the yams after they finish cooking, so the herbs remain fresh-tasting and crisp. Herbs that work particularly well with yam sweet potatoes include basil, bay leaf, chives, cilantro, dill, parsley, rosemary, sage and thyme.
Warm spices add hints of complementary sweetness to yam sweet potato recipes. Their warm flavors deepen and balance the sugary taste of the yams. Allspice, cinnamon, nutmeg and cardamom work in small quantities to offset the sugary sweetness of the yams with a different sort of sweetness. Sprinkle a small amount of spice directly into a yam dish or create a spicy butter sauce to pour over a yam dish.