Place the tomatoes, jalapeño, garlic, and onion in a cast iron skillet over medium-high heat. Let them cook for 4-5 minutes on each side or until charred all over. (You can also do this in the oven under a broiler.)
Add all of the charred veggies, oregano, cumin, ground coriander, salt and pepper to a blender. Process it until you get a smooth mixture. Season with more salt and pepper, to taste. Set it aside.
Place the potatoes in a microwave-safe container. Cover them with water. Microwave for 7 minutes. Strain the potatoes and set them aside.
Add the vegetable oil to a large pot over medium heat. Add the potatoes and stir. Let the potatoes cook for 6-7 minutes, stirring occasionally, until tender.
Add the beef to the pan and let it cook for 8-10 minutes, stirring often, until browned. Season with the salt and pepper.
Pour in the blended sauce and stir to combine. Let it simmer, stirring occasionally, for 15 to 20 minutes.
Stir the cheese into the pot. Let it melt completely. Adjust the seasoning with more salt and pepper, to taste. Serve immediately.
Storage: Once fully cooled, refrigerate any leftovers in an airtight container for up to 5 days.Reheat: Pop it into the microwave for 30 seconds, stir it, and microwave it for another 30 seconds or up to a minute. You can also heat it in a pan over medium-low heat for 7-8 minutes, stirring occasionally.Add veggies. Dice 1 medium zucchini and 2 medium carrots. Sauté them over medium heat for 5 to 6 minutes before cooking the potatoes. Continue with the recipe as usual. This way you can add more veggies to each bite!Jalapeño: Remove the seeds and membrane from the inside of the jalapeño if you want your Carne Guisada to be mild in heat. If you want to have some heat, leave the seeds in the jalapeño. Make it spicy. Add a chile de arbol (or two!) to the mixture as it simmers and stir occasionally. The chiles will release their spice and you’ll love the kick of heat they add. Or you can substitute the jalapeño for a serrano chile. Thicken: Simmering the stew for longer will help the sauce reduce and thicken. The melty cheese should also give the sauce a thicker consistency. However, if you'd like to make it even thicker, you can make a cornstarch slurry by whisking together 2 teaspoons of cornstarch in 2 tablespoons of water. Stir in the slurry as the mixture simmers. Cook the recipe as usual.