Preheat oven to 425 degrees. In a roasting pan, combine asparagus, fennel, onion and olive oil. Sprinkle a healthy amount of salt. Roast about 1 hour or until vegetables are browned and cooked through. Remove from the oven and set aside.
In a blender, combine roasted vegetables, broth, lemon juice, salt and freshly ground pepper to taste. Blend until silky smooth. Reheat in a saucepan before serving. Garnish with fennel fronds.
Recipe by Prepgreen at https://www.prepgreen.com/roasted-asparagus-and-fennel-soup/