01 - Heat the vegetable oil in a large skillet over medium heat until it shimmers.
02 - Add the chopped onion and sauté for 3 to 4 minutes, stirring occasionally, until translucent and softened.
03 - Stir in the minced garlic and finely chopped chiles. Cook for another 2 minutes until fragrant.
04 - Add the diced tomatoes and cook, stirring frequently, for about 5 minutes until the tomatoes soften and release their juices, forming a rustic sauce base.
05 - Add the cubed potatoes, ground cumin, salt, and black pepper. Stir well to coat everything evenly in the sauce.
06 - Pour in about 3/4 cup water, just enough to partially cover the potatoes. Bring to a simmer, then cover the skillet and cook for 15 to 20 minutes, stirring occasionally, until the potatoes are fork-tender and the sauce has thickened.
07 - Taste and adjust the seasoning as needed. Garnish with fresh chopped cilantro if desired. Serve hot with warm tortillas or use as a taco filling.