01 - Heat the vegetable oil in a large skillet over medium heat until it shimmers.
02 - Add the finely chopped onion and sauté for 3 to 4 minutes, stirring occasionally, until soft and translucent.
03 - Stir in the minced garlic and chopped chiles. Cook for 2 minutes until fragrant, being careful not to brown the garlic.
04 - Add the diced tomatoes and cook, stirring frequently, for about 5 minutes until they soften and release their juices, forming a rustic sauce base.
05 - Add the cubed potatoes, ground cumin, salt, and black pepper. Stir thoroughly to coat all the potatoes evenly in the sauce.
06 - Pour in 3/4 cup of water, just enough to partially cover the potatoes. Bring to a gentle simmer.
07 - Cover the skillet and cook for 15 to 20 minutes, stirring occasionally, until the potatoes are fork-tender and the sauce has thickened and clings to the potatoes.
08 - Taste and adjust the seasoning as needed. Garnish with fresh chopped cilantro if desired. Serve hot with warm tortillas or use as a filling for tacos.