In a large pot, add the diced potatoes and add enough cold water to just cover.  Bring to a boil, and cook for 8-10 minutes until potatoes are tender and can be pierced with a fork.

Meanwhile, add the bell pepper, celery, carrots, onion, dill, and parsley to a large mixing bowl.

Once potatoes are finished, drain and rinse with cool water to stop cooking.  Add the cooled potatoes to the mixing bowl with the vegetables.

In a blender, add all the dressing ingredients and blend for 30 seconds to mix.

Toss dressing in with potatoes and vegetables, and stir to coat.

To Make this Recipe Ahead: follow steps 1-3, and cover and chill the potatoes overnight. Perform steps 4 and 5 right before serving to ensure your dressing stays fresh. The avocado may oxidize when exposed to air and brown, so ensure you make dressing right before serving.