Wash potatoes well and place in a large pot. Cover with cold water and bring to a simmer. Simmer gently for 30–35 minutes or until potatoes are cooked.
Strain into a large colander in the sink. Let sit and steam for 2 minutes then transfer back to pot and mash with a large fork or potato masher.
Season with sea salt and pepper.
Drizzle half the olive oil onto the potatoes and fold in. Repeat with the rest of the oil and mix well.
Taste and adjust seasoning with salt and pepper.
Makes about 8 cups