Add 2 lb beef into an Instant Pot along with the onion, 3 carrots, 2 cloves garlic, 2 stalks celery, 2 tsp salt, 1 tsp pepper, and 1 packet Sazon. Pour water into the Instant Pot (see alternative in step 2) until everything is covered by about 1 inch of water.
Put the lid on the Instant Pot and set the timer for 50 minutes. Alternatively, you can put it in a large pot on the stove, cover, and simmer for 2 ½ hours.
When the timer is up, allow for a natural release then remove the meat from the Instant Pot and use two forks to shred the meat. Reserve the beef broth you just created!
Add a large pan to the stove over medium heat and add the olive oil until warm.
Next add the diced onion and saute for 4-5 minutes until the onions begin to turn translucent. Then add a diced green and red bell pepper as well as the ½ tsp salt, ½ tsp sazon, and ¼ tsp black pepper. Saute for a few more minutes until the vegetables are soft.
Form a hole in the middle of the vegetables and add 2 cloves minced garlic. Saute until fragrant, then mix with the rest of the vegetables in the pan.
Add the beef into the pan along with about 1 ½ cups of the reserved beef broth (more if you have more than 2 lb of meat) and 8 oz tomato sauce. Make sure that the beef is almost completely covered in liquid.
Cook uncovered for another 10 or so minutes until almost all of the liquid has evaporated, stirring occasionally. Top with cilantro.
Serve in arepas or with rice. Enjoy!