How to Make It
Preheat the oven to 450°. Wrap the beets in foil and roast for about 45 minutes, until tender. Let cool slightly, then slip off the skins. Quarter the beets.
In a small saucepan, cover the eggs with 1 inch of water and bring to a boil. Let stand off the heat, covered, for 10 minutes. Drain and transfer the eggs to a bowl of ice water to cool. Peel and quarter the eggs.
In a skillet, toast the pumpkin seeds over low heat, stirring, until they are golden, about 5 minutes.
In a bowl, whisk the sherry vinegar with the mustard. Whisking constantly, drizzle in the olive oil until incorporated. Season the vinaigrette with salt and pepper.
In a bowl, combine the beets, avocado and onion. Add 1/4 cup of the vinaigrette, season with salt and pepper and toss gently. Transfer the salad to plates. Add the eggs and drizzle with 2 tablespoons of the vinaigrette. Wipe out the bowl. Add the lettuce, scallions and the remaining vinaigrette, season with salt and pepper and toss. Mound the greens on the vegetables, garnish with the pumpkin seeds and serve.