In a bowl, combine the cooked pheasant with the next five ingredients and mix well. Heat oil in a large skillet over medium heat, add the pheasant mixture and cook, stirring often, until hot.
Whisk together sour cream, lime juice and sugar
Arrange warm tortillas, two stacked per serving, on a work surface. Top each with pheasant mixture, pico de gallo, shredded lettuce, cheese and radishes. Drizzle the sour cream mixture over each.