Put all of the ingredients, except bell pepper, into a mixing bowl and whisk until well mixed. Refrigerate until ready to use. Scoop into a hollowed out bell pepper to serve.
Bring a large pot of boiling salted water to a boil. Drop the green beans, asparagus spears, and broccoli florets, 1 vegetable at a time, into the boiling water and cook for 1 to 2 minutes or until tender. Immediately remove vegetables to a bowl of ice water to stop the cooking. When cool, drain completely.
Arrange blanched vegetables and all other vegetables as desired on a platter. Serve with the dip.