Working with one orange at a time, set an orange on end; with a small knife, slice off and discard the peel and the white pith. Holding the orange in your hand, use a knife to cut the orange segments away from their membranes **(see Three Chef's Techniques).** Place segments in a bowl and set aside. Over a separate bowl, squeeze the remaining orange pulp to extract any remaining juice. Repeat with the second orange. Whisk 4 tbsp. oil, lemon juice, oregano, and scallions into orange juice and season with salt and pepper; set dressing aside.