make the beef sauce
Place a 20-cm (8-inch) cast iron (oven-proofed) skillet over low heat. Add olive oil, diced onion, and diced pepper. Cook for 5 minutes, then add the meat. Increase the heat and cook for 5 minutes, stirring occasionally. Add the minced garlic, taco seasoning, diced tomatoes, tomato sauce, water (or stock), corn, beans, and jalapenos. Season with salt and pepper and cook over medium heat for 10 minutes.
Place a rack in the middle of the oven and preheat it to 200 °C / 400 °F.
Leave three tablespoons of the sauce in the skillet, and transfer the rest to a large plate. Place a tortilla on top of the sauce in the skillet. Add four tablespoons of the beef sauce and two tablespoons of shredded cheese. Set about 4 tablespoons of shredded cheese aside for the final layer. Repeat the process until you use all the ingredients. When you place the last tortilla on top, spread the sour cream on top and sprinkle with the remaining cheese.