Season chicken with vinegar, 1/2 tsp sazon, adobo and garlic powder and let it sit 10 minutes.
Heat a large deep heavy skillet on medium, add 2 tsp oil when hot.
Add chicken and brown 5 minutes on each side. Remove and set aside.
Place onion, cilantro, garlic, scallions and pepper in mini food processor. Add remaining teaspoon of olive oil to the skillet and sauté onion mixture on medium-low until soft, about 3 minutes.
Add tomato, cook another minute. Add rice, mix well and cook another minute.
Add water, bouillon (be sure it dissolves well) and remaining sazon, scraping up any browned bits from the bottom of the pot.
Taste for salt, should taste salty enough to suit your taste, add more as needed.
Add chicken and nestle into rice, bring to a boil. Simmer on medium-low until most of the water evaporates and you see the liquid bubbling at the top of the rice line, then reduce heat to low heat and cover. Make sure the lid has a good seal, no steam should escape (You could place a piece of tin foil or paper towel in between the lid and the pot if steam escapes).
Cook 20 minutes without opening the lid. Shut heat off and let it sit with the lid on an additional 10 minutes (don't peak!!!) Fluff with a fork and eat!
Leftovers can be frozen for up to 6 months. To reheat, thaw in the refrigerator the night before, then heat in the microwave or oven.