Preheat the oven to 400 degrees F.
Place each beet on an individual piece of aluminum foil. Drizzle the beets with 1 tablespoon olive oil and season with 1/2 teaspoon kosher salt and 1/4 teaspoon pepper. Fold into loose packets and place on a sheet pan. Roast the beets for 45-50 minutes until they can be easily pierced with a knife.
When the beets are cool enough to handle, use a towel to rub off their skins. Cut the beets into a 1/2-inch dice.
Cut the skin and white pith off the oranges. Slice between the membranes removing the segments while collecting the juice in a small bowl. Dice the orange segments.
For the salad, combine the roasted beets, oranges, kale, coleslaw mix, avocados, red onions and almonds in a large bowl.
For the vinaigrette, whisk the garlic, mustard, 1/2 teaspoon kosher salt, 1/4 teaspoon black pepper, vinegar, 1/4 cup olive oil and 1 tablespoon of the reserved juice from the oranges.
Drizzle the vinaigrette into the salad. Gently toss to combine. Some of the color of the beets will stain the salad.