How to Make It
Preheat the oven to 350°. In a small baking dish, rub the beets with olive oil. Add the water and season with salt and white pepper. Cover tightly with foil and roast for 2 to 2 1/2 hours, or until tender when pierced with a knife. Let cool, then peel the beets and cut them into 3/4-inch pieces. Transfer to a large bowl.
Meanwhile, in a blender, combine the chopped onion with the red wine vinegar, lemon juice, mustard and honey. Season with salt and white pepper and blend until smooth. With the machine on, add the grapeseed oil and the 2 tablespoons of olive oil in a steady stream.
Add the avocado to the roasted beets. Pour the onion dressing on top and toss gently to combine. Season the salad with salt and pepper and serve.