Peel the onion and cut into small cubes that are about ¼ inch thick. Do the same with the peppers and cut them into small cubes. This is just a rough chop, no need to be exact. Set them to the side for later.
Take the chicken and remove any excess fat the thighs may have. Add the chicken to a bowl and add the adobo, sazon, chicken bouillon, oregano, and garlic paste. Mix until all the chicken is seasoned.
In a medium-sized pan, add the oil over high heat. Add the chicken and sear for 12 minutes. Flip the chicken a couple of times to brown evenly.
Reduce your heat to medium-high. Make space in the middle and add the vegetables, sofrito, and tomato sauce. Stir and finish cooking covered for 8 minutes.
If you have a chicken shredder, you can shred the chicken right away. If not, let the chicken cool to the touch and then pull it apart.
Serve the shredded chicken, and don't forget to add all the cooked vegetables on top. Enjoy!
Notes
I used chicken thighs because they're the juiciest cut of the chicken and hold more heat, but you can use chicken breast.