Cut chicken breasts into bite-sized cubes. Toss with Adobo, Sazon, chopped onions, and green onions. Let sit 15 mins (or up to 2 hours if time allows).
Heat oil in a large, heavy pot (with a lid) over medium heat.Add white sugar and let it melt. Once it turns a burnt colour (about 4-5 mins), add chicken. Stir well to coat the chicken in the caramelized sugar. Cook for 5-6 mins until lightly browned.
Add rinsed rice, stirring to toast it slightly in the flavors. Pour in chicken stock, scraping any browned bits from the bottom. Bring to a boil, then reduce to low heat, cover, and simmer for 20-25 mins (until rice is tender and liquid is absorbed).
Turn off heat, fluff rice gently, and let sit covered for 5-10 mins.