Source: Farmer John’s Cookbook: The Real Dirt on Vegetables by John Peterson and Angelic Organics
Place parsnips and potatoes in a pot and cover with cold water, Add 1 teaspoon of salt and bring to a boil uncovered. Reduce heat and simmer vegetables, lightly covered, until tender, about 15 minutes.
Reserve 1 cup of the cooking water, then drain the vegetables. Return vegetables to the pot and coarsely mash with a potato masher or fork. Add olive oil, remaining teaspoon of sea salt, fresh herbs and black pepper to taste. Add a little of the reserved water to achieve desired consistency. Adjust seasoning to taste.