Preheat the oven to 400°F.
Wash the beats, drizzle with olive oil and wrap in aluminum foil. Place on a baking sheet and a roast for one hour or until fork tender.
Once fork tender, removed from the oven and let them cool to room temperature. Then using a paring knife, remove the skin. Some of the skin will peel off but some may need to be cut off. Cut the beats into 1/2 inch thick rounds. If the beets are very large cut the rounds in half. Set aside.
Cut the skin completely off of the oranges with a paring knife. Making sure to remove all of the pith. Cut the oranges in 1/2 inch round discs. Set aside.
Thinly slice the red onion. Set aside.
To make the dressing, combine olive oil, white wine vinegar, salt, pepper, Dijon, mustard and garlic powder. Whisk vigorously to combine. Set aside.
Dress the arugula with some of the dressing and lay it down on your serving dish. Then top with alternating slices of beets and oranges. Add the red onion, walnuts, and Gorgonzola crumbles on top.
Drizzle with more dressing and serve!