Cook potatoes: Peel and cut potatoes into chunks, place in a pot, cover with cold salted water, bring to a boil, and cook until very tender, about 10-15 minutes. Drain well.

Mash potatoes with butter, sour cream, salt, garlic powder, and onion powder until creamy. Add milk as needed, to make them smooth. Stir in the shredded cheese.

Warm tortillas (so they don’t crack) Heat a dry skillet over medium heat and warm corn tortillas for 15–20 seconds per side until soft and flexible, then place in a tortilla warmer or wrap in a clean dish towel to keep warm.

Assemble: Add about 3 tablespoons potato filling to each tortilla and fold gently in half.

Pan fry: Pour about 1/2 inch oil into a skillet and heat over medium heat (until the oil reaches 350°F or a tortilla edge sizzles immediately when dipped into the oil). Fry tacos 2–3 at a time for about 2 minutes on the first side and 1–2 minutes on the second side until golden brown and crispy, then transfer to paper towels or a wire rack.

Serve warm, with salsa, sour cream, lettuce, lime wedges, and cotija or queso fresco if desired.