You've been asked to make a soup and use cornstarch for thickening. How should the cornstarch be added?

A. Sift over the soup before bringing it to a simmer
B. Temper with broth in a separate bowl before adding to pot
C. Saute with oil before adding soup ingredients
D. Combine with melted butter and slowly add to soup
E. Mix with equal parts water and add when soup is simmering