Start by cutting the beef into thin strips and seasoning with salt and pepper. After that, peel the potatoes, wash them, and cut them into small cubes or a half moon shapes and set aside.
The next step is to cook 2 of the tomatoes and onions in a cup of water over medium heat. Once they are cooked, let them cool and blend them in a blender with 1/4 of the onion, one clove of garlic, and a tablespoon of salt. Then set the resulting salsa aside for later.
Next, chop the remaining tomatoes in a half moon shape, slice the serrano or jalapeno peppers and the rest of the onion. Set this aside as well.
In a large skillet, add the olive oil and heat it up on the stove over medium heat. When it is hot enough, add the steak strips, the two remaining cloves of garlic, and the sliced onion and let cook for about 5 minutes.
Once the beef is cooked through, add the potatoes and lower the heat to medium-low. When the potatoes start to brown slightly, add the rest of vegetables and chiles and mix well, cooking for another 5 minutes.
Finally, add the salsa that you prepared earlier and the cilantro and bring it to a boil for another 5 minutes. Add salt to taste and serve with rice, refried beans, and warm corn tortillas.