Precooked cornmeal, ground from cooked corn kernels, is the key to quick tamales. Don't confuse this with standard cornmeal, which is made from dried uncooked corn kernels. Goya's precooked cornmeal, also called masarepa, is the most widely available. P.A.N., from Venezuela, is another good brand. For information on stores near you, call 800-275-4692.