Wash the potatoes an put them in a large pot with cold water and 1 teaspoon of salt.. The water should completely cover the potatoes. Do not remove the skin from the potatoes.
Bring the water to a boil and let the potatoes cook until a fork penetrates without much effort.
Drain the hot water and rinse the potatoes under cold water.
Cut the potatoes in pieces of about 1 1/2 inch in each side and put them in a large bowl.
Add the tomatoes, the extra virgin olive oil and the oregano. Add salt and pepper as desired.
Toss everything gently so as to not brake the potatoes.