For beets: Preheat oven to 400°F. Trim ends off beets but do not remove the skin. Wrap beets in foil and place on baking sheet. Roast beets until tender, about 1 hour. Set aside to cool.
To make salad dressing: Blend grape seed oil, olive oil, honey, vinegar, garlic, oregano, mustard, salt and pepper in blender until thick and emulsified. Transfer to a small glass pitcher.
Rinse onion slices under cold water to remove excess bitterness and pat dry. Place in a small bowl and spoon some of the dressing over onions and toss to combine.
Peel skin off beets. Cut the beets in wedges shaped like half moons (about 6-8 wedges per beet.)
Remove the onions from the dressing leaving extra dressing in the bowl. Place onions in a large bowl.
Add beets to the bowl. Spoon some of the dressing over the top and mix to combine. Add half of the nuts and mix one more time. Add more dressing to taste.
Line platter or salad plates with arugula lightly tossed with dressing. Top with beet mixture, feta cheese, fresh oregano and remaining nuts.
Sweet & Spicy Roasted Pecans
Lower oven temperature to 350°F. Cover a rimmed baking sheet with baking spray.
Combine salt, pepper, red pepper flakes, brown sugar, chili powder and cumin in a small bowl.
Place grape seed oil and butter in a large frying pan and melt on low heat. Add pecans and toss to coat. Sprinkle in combined spices and stir to coat. Spread nuts on baking sheet and toast for 10-12 minutes. Remove from oven and set aside to cool.