* Beet should be washed and dried. If you are using a fresh beet, preheat the oven to 375 Degrees F. Wrap the beet in aluminum foil and bake until tender, about 1 1/4 hours. When the beet is cool enough to handle, peel it and cut into 1/2-inch dice. Meanwhile, cook the potatoes in lightly salted boiling water for 10 minutes. Add the carrots and cook until the vegetables are tender, but not mushy, about 10 minutes more. Let cool until easy to handle, then cut the vegetables into 1/2-inch dice. In a large salad bowl, combine the potatoes, carrots, onion, pickles, peas, beet, scallions, and dill. Season with salt and pepper and toss gently, taking care not to crush the vegetables. In a small bowl, whisk the dry mustard, sugar and vinegar together. Whisk in the oil and season with salt and pepper. Toss the salad with the dressing and tasting to correct the seasoning. Cover and refrigerate for at least 30 minutes before serving. Makes 4 generous servings.