In a bowl, add the beef, garlic, sofrito, naranja agria, adobo, oregano, and salt. Mix until the beef is well coated with the seasonings.
Heat oil in a pot over medium heat and sprinkle the sugar evenly into the pot. The sugar will melt quickly and start to caramelize, turning light brown. As soon as this happens, quickly add the beef to prevent the sugar from burning.
Cook until browned on both sides and the beef has absorbed most of it's juices, about 5 minutes.
Turn the beef pieces, add ½ cup of water and continue cooking covered until most juices are absorbed, about 5-8 minutes. Repeat this step one more time
Add the onion slices and cook uncovered for 2-3 minutes, or until they soften and are slightly charred.
Add tomato paste and 1 cup of water to the pot and continue cooking covered until half of the liquid evaporates and the meat and onions are tender, or about 10-15 minutes. ¡Buen provecho!