Ground beef and potatoes cooked in a tomato sauce is a dish known as picadillo sencillo, or carne molida con papas. All the ingredients are usually chopped before cooking. “Chopping” in Spanish is “picar” or “cortar”, which is where the dish gets its name.
Heat oil in a large skillet; once oil is hot add the ground meat to cook. Break up large lumps of meat using a wooden spoon to make sure all the little pieces are well cooked. Fry until brown, about 8 minutes.
Add the onion and garlic. Stir and cook for about 1 minute, just enough to allow the onion to get transparent, then add Serrano pepper plus diced potatoes. Stir and keep cooking until potatoes are slightly tender, but still firm. This will take about 5 more minutes since you will still keep cooking them when you add the tomatoes.
Now, add the diced tomatoes and Knorr beef bouillon and stir again. The tomatoes will release their juices and the beef bouillon will dissolve, adding more flavor to the picadillo. Place a lid on your skillet and lower the heat. Keep cooking the picadillo until your potatoes are completely cooked and the tomatoes have formed a thick sauce.
Finally, season with salt and pepper and add the chopped cilantro.
Serve with rice and warm corn tortillas. Enjoy!