Place the diced potatoes in a large pot and cover with water. Bring the water to a boil and cook the potatoes until they are soft, about 15-20 minutes.
Drain the potatoes and mash them with a fork or potato masher.
Add the diced onion, minced garlic, cumin, paprika, chili powder, salt, and pepper to the mashed potatoes and mix well.
Add two to three heaped tablespoons of the potato mixture to a warm tortilla and fold in half. Repeat this until all of your mashed potato has been used up.
Heat two spoonfuls of oil in a large skillet over medium-high heat.
Place the tacos into the skillet and cook, for about 2-3 minutes on each side, or until the outside becomes crispy and golden brown.
Top with shredded lettuce, shredded cheddar cheese, and salsa.
Serve the tacos hot, with sour cream and extra salsa as desired.