Heat oil in a medium saucepan over medium-low heat. Stir in diced onions, chicken bouillon, Sazón seasoning and saffron. Saute until soft, 5 minutes. Stir in diced bell peppers, tomatoes (See Note 1). Stir to mix and cook 5 minutes more.
Add rice to the pot, stirring to coat. Cook rice a minute or two. Pour in 2 cups hot water, stir to combine. Bring to a boil, lower heat to medium-low and simmer 25 minutes, covered, or until rice is tender and water is absorbed completely.
Remove lid, fluff with fork and add frozen peas and pimentos. Toss to mix in and cover. Allow to rest 5 minutes. Fluff again, season to taste if needed and serve.
Notes
1. I have also made this substituting the bell peppers and tomato for 1/3 cup GOYA Sofrito (tomato based sauce). Follow recipe instructions the same.