In a large skillet, heat 2 tablespoons of the oil on medium-low. Add the onions and while occasionally stirring, cook until softened and beginning to brown, about 5 minutes. Add the garlic and cook for 30 more seconds.

Stir in the salt, ground cumin, and pepper, then add the potatoes. Stir the potatoes until well combined with the onions and garlic.

Pour the water into the skillet, then cover. Cook the potatoes covered for 10 minutes.

After 10 minutes, remove the lid. While occasionally stirring, continue cooking the potatoes until the water is reduced, about 5 minutes. Stir in the remaining tablespoon of oil and then add the green chile strips and tomatoes.

While occasionally stirring, continue to cook until the potatoes are beginning to crisp and the tomatoes are softened, about 5 minutes. Taste and adjust seasonings if desired. Serve warm.