Place sliced potatoes into a saucepan and cover with water. Bring to a boil and cook for about 20 minutes, or until tender. Drain.
Heat oil over medium high. Add potatoes, onion and chili peppers and cook for 12 minutes, using the back of your spoon to break apart the potatoes. Reduce heat to medium low and add garlic, cumin, paprika and salt. Stir for 2 minutes. Remove from heat and transfer to a bowl. Add yogurt or sour cream and mash with the back of a fork or a potato masher. Garnish with cilantro and serve warm.