Preheat the oven to 400° F. Line a baking pan with parchment paper.
Toss diced sweet potatoes with 1 tablespoon olive oil, ½ teaspoon kosher salt and ¼ teaspoon black pepper on the prepared baking pan and spread into a single layer. Roast for 25 minutes until the sweet potatoes are tender and slightly browned at the edges.
In a large bowl, combine the lettuce, apples, celery, green onions, pumpkin seeds, pecans, grapes, blue cheese, parsley, dill and sweet potatoes.
For the vinaigrette, place all ingredients in a jar with a tight fitting lid and shake, shake, shake.
Drizzle the vinaigrette in the salad before serving.