To prepare this delicious Greek potato stew recipe (patates yahni), start by preparing your vegetables. Peel and cut the potatoes into 2.5 cm chunks, finely chop (or grate) the onion and garlic and set aside. Peel the tomatoes and grate. You may find it easier to peel the tomatoes if you blanch them first for 1 minute in hot water. (For this Greek potato stew recipe, it is best to use fresh tomatoes rather than canned.).
Heat a large pot over medium-high heat. Add the olive oil and onion and sauté until softened. Stir in the garlic and sauté for 1 more minute. Add the tomato paste and cook for 1 more minute.
In the same pot add the grated tomatoes, the potatoes, sprinkle with chopped parsley and season with salt and pepper. Add just enough warm water to cover the potatoes (whilst stirring ocassionally) and bring to the boil. Turn the heat down to medium, cover and simmer for 30 minutes or until the potatoes are tender.
Greek potato stew (Patates Yahni) is best served while still warm or at room temperature. Enjoy!