Slice Belgian endive right before serving, as it tends to discolor when exposed to air. All the other ingredients and the vinaigrette can be prepared hours ahead of time and chilled, covered.
With a small, sharp knife, cut ends off oranges. Set 1 orange, cut side down, on a cutting board. Following its curve with the knife, slice off peel and white pith. Cut between inner membranes and fruit to release segments; drop segments into bowl. Repeat with remaining oranges.
Rinse and dry watercress. In a large bowl, toss watercress, Belgian endive, and oranges with just enough vinaigrette to coat. Divide among 12 salad plates and garnish each salad with pomegranate seeds and toasted almonds.
Note: Nutritional analysis is per serving, with vinaigrette.