Place split English muffin halves in a greased 13"x9" baking pan. Use a 1 1/2" to 2" cutter to cut a hole in the center of each muffin half. Place the cutouts next to muffins in baking pan. Crack open eggs and carefully put one egg in the center of each muffin hole. Move pan to preheated oven. Bake for 12 t 15 minutes or until eggs are just set.
Meanwhile, for dressing:
In a small bowl whisk together the orange juice, vinegar, sugar, if using, olive oil, mustard, salt, and pepper. Gradually whisk in sour cream. Divide mesclun among four dinner plates. Place 1 egg filled muffin half atop greens. Cut remainig rounds from muffin halves into wedges and sprinkle around eggs. Drizzle with the dressing. Add walnuts and orange wedges. Enjoy!
To toast walnuts, place them in a shallow baking pan. Bake in a preheated 350*F. oven for 5 to 7 minutes, shaking the pan once or twice.